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Communication disorder

A communication disorder is any disorder that affects an individual's ability to comprehend, detect, or apply language and speech to engage in dialogue effectively with others. This also encompasses deficiencies in verbal and non-verbal communication styles. The delays and disorders can range from simple sound substitution to the inability to understand or use one's native language. This article covers subjects such as diagnosis, the DSM-IV, the DSM-V, and examples like sensory impairments, aphasia, learning disabilities, and speech disorders.

Diagnosis
Disorders and tendencies included and excluded under the category of communication disorders may vary by source. For example, the definitions offered by the American Speech–Language–Hearing Association differ from those of the Diagnostic Statistical Manual 4th edition (DSM-IV).

Gleason (2001) defines a communication disorder as a speech and language disorder which refers to problems in communication and in related areas such as oral motor function. The delays and disorders can range from simple sound substitution to the inability to understand or use one's native language. In general, communication disorders commonly refer to problems in speech (comprehension and/or expression) that significantly interfere with an individual's achievement and/or quality of life. Knowing the operational definition of the agency performing an assessment or giving a diagnosis may help.

Persons who speak more than one language or are considered to have an accent in their location of residence do not have a speech disorder if they are speaking in a manner consistent with their home environment or that is a blending of their home and foreign environment.

Other conditions, as specified in the Cincinnati Children's Health Library (2019), that may increase the risk of developing a communication disorder include:

 * Cleft lip or cleft palate - a disorder that is caused by the failure of the parts of the mouth and palate to form together while a fetus is developing in the womb, which then creates a deformity. This is often corrected by surgery.
 * Craniofacial anomalies - a deformity of a child's facial bone structure and head bones that is caused by early or delayed fusion of the bones.
 * Velopharyngeal insufficiency - when the soft palate does not make a tight enough seal against the pharynx and creates a nasally sound while speaking.
 * Dental malocclusion - when the top and bottom teeth do not align when the mouth is closed.
 * Oral-motor dysfunction - a disconnection between the brain and the mouth that results in the inability to perform tasks such as chewing, blowing, talking, among others.
 * Neurological disease/dysfunction - a blanket term that encompasses multiple neurological disorders like dementia, Alzheimer's, epilepsy, and multiple sclerosis.
 * Brain injury - when the brain is damaged in a traumatic event that makes the brain move around in the skull.
 * Respirator dependency - the inability to breathe without the use of a ventilator machine.
 * Respiratory compromise - the declination of respiratory function that can lead to failure or even death if it is left untreated.
 * Tracheostomy - a surgical hole created in the trachea to assist in breathing.
 * Vocal fold pathology - an abnormality of the cartilage on the vocal folds.
 * Developmental delay - when a child fails to develop (whether that be mentally or physically) at the normal rate for children at the same age.
 * Autism - a term that includes neurological disorders that inhibit social functioning, communication, sensory processing, and other challenges.
 * Prematurity or traumatic birth - an early (before full term) birth, or one with complications.
 * Hearing loss or deafness - when the auditory system does not function as it normally should, and there is a decrease in hearing.

DSM-IV
According to the DSM-IV-TR (no longer used), communication disorders were usually first diagnosed in childhood or adolescence, though they are not limited as childhood disorders and may persist into adulthood. They may also occur with other disorders.

Diagnosis involved testing and evaluation during which it is determined if the scores/performance are "substantially below" developmental expectations and if they "significantly" interfere with academic achievement, social interactions, and daily living. This assessment might have also determined if the characteristic is deviant or delayed. Therefore, it may have been possible for an individual to have communication challenges but not meet the criteria of being "substantially below" criteria of the DSM IV-TR. The DSM diagnoses did not comprise a complete list of all communication disorders, for example, auditory processing disorder is not classified under the DSM or ICD-10. The following diagnoses were included as communication disorders:
 * Expressive language disorder – characterized by difficulty expressing oneself beyond simple sentences and a limited vocabulary. Individuals can better understand than use language; they may have a lot to say, but have more difficulty organizing and retrieving the words than expected for their developmental stage.
 * Mixed receptive-expressive language disorder – problems comprehending the commands of others.
 * Stuttering – a speech disorder characterized by a break in fluency, where sounds, syllables, or words may be repeated or prolonged.
 * Phonological disorder – a speech sound disorder characterized by problems in making patterns of sound errors (e.g., "dat" for "that").
 * Communication disorder NOS (not otherwise specified) – the DSM-IV diagnosis in which disorders that do not meet the specific criteria for the disorder listed above may be classified.

DSM-5
The DSM-5 diagnoses for communication disorders completely rework the ones stated above. The diagnoses are made more general in order to capture the various aspects of communications disorders in a way that emphasizes their childhood onset and differentiate these communications disorders from those associated with other disorders (e.g. autism spectrum disorders).
 * Language disorder – the important characteristics of a language disorder are difficulties in learning and using language, which is caused by problems with vocabulary, with grammar, and with putting sentences together in a proper manner. Problems can both be receptive (understanding language) and expressive (producing language).
 * Speech sound disorder – previously called phonological disorder, for those with problems with pronunciation and articulation of their native language.
 * Childhood-Onset Fluency Disorder (Stuttering) - standard fluency and rhythm of speech is interrupted, often causing the repetition of whole words and syllables. May also include the prolongation of words and syllables; pauses within a word; and/or the avoidance of pronouncing difficult words and replacing them with easier words that the individual is better able to pronounce. This disorder causes many communication problems for the individual and may interfere with social communication and performance in work and/or school settings where communication is essential.
 * Social (pragmatic) communication disorder – this diagnosis described difficulties in the social uses of verbal and nonverbal communication in naturalistic contexts, which affects the development of social relationships and dialogue comprehension. The difference between this diagnosis and autism spectrum disorder is that in the latter there is also a restricted or repetitive pattern of behavior.
 * Unspecified communication disorder – for those who have symptoms of a communication disorder but who do not meet all criteria, and whose symptoms cause distress or impairment.

Examples
Examples of disorders that may include or create challenges in language and communication and/or may co-occur with the above disorders:
 * autism spectrum disorders - autistic disorder, pervasive developmental disorder not otherwise specified (PDDNOS), and Asperger disorder – developmental disorders that affect the brain's normal development of social and communication skills.
 * expressive language disorder – affects speaking and understanding where there is no delay in non-verbal intelligence.
 * mixed receptive-expressive language disorder – affects speaking, understanding, reading and writing where there is no delay in non-verbal intelligence.
 * specific language impairment – a language disorder that delays the mastery of language skills in children who have no hearing loss or other developmental delays. SLI is also called developmental language disorder, language delay, or developmental dysphasia.

Sensory impairments

 * Blindness – A link between communication skills and visual impairment with children who are blind is currently being investigated.
 * Deafness/frequent ear infections – Hearing impairments during language acquisition may lead to spoken language problems. Children with frequent ear infections may temporarily develop problems pronouncing words correctly. The inability to hear is not in itself a communication disorder.

Aphasia
Aphasia is loss of the ability to produce or comprehend language. There are acute aphasias which result from stroke or brain injury, and primary progressive aphasias caused by progressive illnesses such as dementia.
 * Acute aphasias
 * Expressive aphasia also known as Broca's aphasia, expressive aphasia is a non-fluent aphasia that is characterized by damage to the frontal lobe region of the brain. A person with expressive aphasia usually speaks in short sentences that make sense but take great effort to produce. Also, a person with expressive aphasia understands another person's speech but has trouble responding quickly.
 * Receptive aphasia also known as Wernicke's aphasia, receptive aphasia is a fluent aphasia that is categorized by damage to the temporal lobe region of the brain. A person with receptive aphasia usually speaks in long sentences that have no meaning or content. People with this type of aphasia often have trouble understanding other's speech and generally do not realize that they are not making any sense.
 * Conduction aphasia also known as association aphasia, is when there is a difficulty repeating words or phrases. Comprehension and spontaneous speech are usually not limited, just repetition.
 * Anomic aphasia is when one has difficulty retrieving words and may take long pauses when trying to recall certain verbs or nouns. This is a mild form of aphasia as comprehension is not limited.
 * Global aphasia is the most severe form of aphasia as there is difficulty with speech comprehension, as well as difficulty in responding in meaningful ways. This is caused by several brain injuries in more than one spot.
 * Primary progressive aphasias (PPA)
 * Progressive nonfluent aphasia also known as PNFA, is a form of PPA that involves a reduction of speech fluency, syntax and grammar impairment, difficulty of articulation and word finding, and long-term comprehension.
 * Semantic dementia is a condition in which words and phrases slowly begin to lose meaning, and comprehension is lost because of a deterioration in the semantic memory. This is usually characterized by behavior changes, fluent speech but with no meaning, preserved syntax and grammar, and the impaired ability to recognize objects.
 * Logopenic progressive aphasia also known as LPA, is associated with Alzheimer's disease. This is characterized by difficulty in word retrieval and repetition, phonological errors, anomia, and the preservation of single-word comprehension.

Learning disability

 * Dyscalculia – an impairment in the systems used in communicating numbers
 * Dyslexia – an impairment in systems used in reading
 * Dysgraphia – an impairment in the systems used in writing

Speech disorders

 * cluttering - a syndrome characterized by a speech delivery rate which is either abnormally fast, irregular, or both.
 * dysarthria - a condition that occurs when problems with the muscles that helps a person to talk make it difficult to pronounce words.
 * esophageal voice - involves the patient injecting or swallowing air into the esophagus. Usually learnt and used by patients who cannot use their larynges to speak. Once the patient has forced the air into their esophagus, the air vibrates a muscle and creates esophageal voice. Esophageal voice tends to be difficult to learn and patients are often only able to talk in short phrases with a quiet voice.
 * lisp - a speech impairment that is also known as sigmatism.
 * speech sound disorder - Speech-sound disorders (SSD) involve impairments in speech-sound production and range from mild articulation issues involving a limited number of speech sounds to more severe phonologic disorders involving multiple errors in speech-sound production and reduced intelligibility.
 * stuttering - a speech disorder in which sounds, syllables, or words are repeated or last longer than normal. These problems cause a break in the flow of speech (called disfluency).

title: Communication disorder


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Inner ear

The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:
 * The cochlea, dedicated to hearing; converting sound pressure patterns from the outer ear into electrochemical impulses which are passed on to the brain via the auditory nerve.
 * The vestibular system, dedicated to balance.

The inner ear is found in all vertebrates, with substantial variations in form and function. The inner ear is innervated by the eighth cranial nerve in all vertebrates.

Structure
The labyrinth can be divided by layer or by region.

Bony and membranous labyrinths
The bony labyrinth, or osseous labyrinth, is the network of passages with bony walls lined with periosteum. The three major parts of the bony labyrinth are the vestibule of the ear, the semicircular canals, and the cochlea. The membranous labyrinth runs inside of the bony labyrinth, and creates three parallel fluid filled spaces. The two outer are filled with perilymph and the inner with endolymph.

Vestibular and cochlear systems
In the middle ear, the energy of pressure waves is translated into mechanical vibrations by the three auditory ossicles. Pressure waves move the tympanic membrane which in turns moves the malleus, the first bone of the middle ear. The malleus articulates to incus which connects to the stapes. The footplate of the stapes connects to the oval window, the beginning of the inner ear. When the stapes presses on the oval window, it causes the perilymph, the liquid of the inner ear to move. The middle ear thus serves to convert the energy from sound pressure waves to a force upon the perilymph of the inner ear. The oval window has only approximately 1/18 the area of the tympanic membrane and thus produces a higher pressure. The cochlea propagates these mechanical signals as waves in the fluid and membranes and then converts them to nerve impulses which are transmitted to the brain.

The vestibular system is the region of the inner ear where the semicircular canals converge, close to the cochlea. The vestibular system works with the visual system to keep objects in view when the head is moved. Joint and muscle receptors are also important in maintaining balance. The brain receives, interprets, and processes the information from all these systems to create the sensation of balance.

The vestibular system of the inner ear is responsible for the sensations of balance and motion. It uses the same kinds of fluids and detection cells (hair cells) as the cochlea uses, and sends information to the brain about the attitude, rotation, and linear motion of the head. The type of motion or attitude detected by a hair cell depends on its associated mechanical structures, such as the curved tube of a semicircular canal or the calcium carbonate crystals (otolith) of the saccule and utricle.

Development
The human inner ear develops during week 4 of embryonic development from the auditory placode, a thickening of the ectoderm which gives rise to the bipolar neurons of the cochlear and vestibular ganglions. As the auditory placode invaginates towards the embryonic mesoderm, it forms the auditory vesicle or otocyst.

The auditory vesicle will give rise to the utricular and saccular components of the membranous labyrinth. They contain the sensory hair cells and otoliths of the macula of utricle and of the saccule, respectively, which respond to linear acceleration and the force of gravity. The utricular division of the auditory vesicle also responds to angular acceleration, as well as the endolymphatic sac and duct that connect the saccule and utricle.

Beginning in the fifth week of development, the auditory vesicle also gives rise to the cochlear duct, which contains the spiral organ of Corti and the endolymph that accumulates in the membranous labyrinth. The vestibular wall will separate the cochlear duct from the perilymphatic scala vestibuli, a cavity inside the cochlea. The basilar membrane separates the cochlear duct from the scala tympani, a cavity within the cochlear labyrinth. The lateral wall of the cochlear duct is formed by the spiral ligament and the stria vascularis, which produces the endolymph. The hair cells develop from the lateral and medial ridges of the cochlear duct, which together with the tectorial membrane make up the organ of Corti.

Microanatomy

Rosenthal's canal or the spiral canal of the cochlea is a section of the bony labyrinth of the inner ear that is approximately 30 mm long and makes 2¾ turns about the modiolus, the central axis of the cochlea that contains the spiral ganglion.

Specialized inner ear cell include: hair cells, pillar cells, Boettcher's cells, Claudius' cells, spiral ganglion neurons, and Deiters' cells (phalangeal cells).

The hair cells are the primary auditory receptor cells and they are also known as auditory sensory cells, acoustic hair cells, auditory cells or cells of Corti. The organ of Corti is lined with a single row of inner hair cells and three rows of outer hair cells. The hair cells have a hair bundle at the apical surface of the cell. The hair bundle consists of an array of actin-based stereocilia. Each stereocilium inserts as a rootlet into a dense filamentous actin mesh known as the cuticular plate. Disruption of these bundles results in hearing impairments and balance defects.

Inner and outer pillar cells in the organ of Corti support hair cells. Outer pillar cells are unique because they are free standing cells which only contact adjacent cells at the bases and apices. Both types of pillar cell have thousands of cross linked microtubules and actin filaments in parallel orientation. They provide mechanical coupling between the basement membrane and the mechanoreceptors on the hair cells.

Boettcher's cells are found in the organ of Corti where they are present only in the lower turn of the cochlea. They lie on the basilar membrane beneath Claudius' cells and are organized in rows, the number of which varies between species. The cells interdigitate with each other, and project microvilli into the intercellular space. They are supporting cells for the auditory hair cells in the organ of Corti. They are named after German pathologist Arthur Böttcher (1831–1889).

Claudius' cells are found in the organ of Corti located above rows of Boettcher's cells. Like Boettcher's cells, they are considered supporting cells for the auditory hair cells in the organ of Corti. They contain a variety of aquaporin water channels and appear to be involved in ion transport. They also play a role in sealing off endolymphatic spaces. They are named after the German anatomist Friedrich Matthias Claudius (1822–1869).

Deiters' cells (phalangeal cells) are a type of neuroglial cell found in the organ of Corti and organised in one row of inner phalangeal cells and three rows of outer phalangeal cells. They are the supporting cells of the hair cell area within the cochlea. They are named after the German pathologist Otto Deiters (1834–1863) who described them.

Hensen's cells are high columnar cells that are directly adjacent to the third row of Deiters' cells.

Hensen's stripe is the section of the tectorial membrane above the inner hair cell.

Nuel's spaces refer to the fluid-filled spaces between the outer pillar cells and adjacent hair cells and also the spaces between the outer hair cells.

Hardesty's membrane is the layer of the tectoria closest to the reticular lamina and overlying the outer hair cell region.

Reissner's membrane is composed of two cell layers and separates the scala media from the scala vestibuli.

Huschke's teeth are the tooth-shaped ridges on the spiral limbus that are in contact with the tectoria and separated by interdental cells.

Blood supply
The bony labyrinth receives its blood supply from three arteries: 1 – Anterior tympanic branch (from maxillary artery). 2 – Petrosal branch (from middle meningeal artery). 3 – Stylomastoid branch (from posterior auricular artery). The membranous labyrinth is supplied by the labyrinthine artery. Venous drainage of the inner ear is through the labyrinthine vein, which empties into the sigmoid sinus or inferior petrosal sinus.

Function
Neurons within the ear respond to simple tones, and the brain serves to process other increasingly complex sounds. An average adult is typically able to detect sounds ranging between 20 and 20,000 Hz. The ability to detect higher pitch sounds decreases in older humans.

The human ear has evolved with two basic tools to encode sound waves; each is separate in detecting high and low-frequency sounds. Georg von Békésy (1899–1972) employed the use of a microscope in order to examine the basilar membrane located within the inner-ear of cadavers. He found that movement of the basilar membrane resembles that of a traveling wave; the shape of which varies based on the frequency of the pitch. In low-frequency sounds, the tip (apex) of the membrane moves the most, while in high-frequency sounds, the base of the membrane moves most.

Disorders
Interference with or infection of the labyrinth can result in a syndrome of ailments called labyrinthitis. The symptoms of labyrinthitis include temporary nausea, disorientation, vertigo, and dizziness. Labyrinthitis can be caused by viral infections, bacterial infections, or physical blockage of the inner ear.

Another condition has come to be known as autoimmune inner ear disease (AIED). It is characterized by idiopathic, rapidly progressive, bilateral sensorineural hearing loss. It is a fairly rare disorder while at the same time, a lack of proper diagnostic testing has meant that its precise incidence cannot be determined.

Other animals
Birds have an auditory system similar to that of mammals, including a cochlea. Reptiles, amphibians, and fish do not have cochleas but hear with simpler auditory organs or vestibular organs, which generally detect lower-frequency sounds than the cochlea. The cochlea of birds is also similar to that of crocodiles, consisting of a short, slightly curved bony tube within which lies the basilar membrane with its sensory structures.

Cochlear system
In reptiles, sound is transmitted to the inner ear by the stapes (stirrup) bone of the middle ear. This is pressed against the oval window, a membrane-covered opening on the surface of the vestibule. From here, sound waves are conducted through a short perilymphatic duct to a second opening, the round window, which equalizes pressure, allowing the incompressible fluid to move freely. Running parallel with the perilymphatic duct is a separate blind-ending duct, the lagena, filled with endolymph. The lagena is separated from the perilymphatic duct by a basilar membrane, and contains the sensory hair cells that finally translate the vibrations in the fluid into nerve signals. It is attached at one end to the saccule.

In most reptiles the perilymphatic duct and lagena are relatively short, and the sensory cells are confined to a small basilar papilla lying between them. However, in mammals, birds, and crocodilians, these structures become much larger and somewhat more complicated. In birds, crocodilians, and monotremes, the ducts are simply extended, together forming an elongated, more or less straight, tube. The endolymphatic duct is wrapped in a simple loop around the lagena, with the basilar membrane lying along one side. The first half of the duct is now referred to as the scala vestibuli, while the second half, which includes the basilar membrane, is called the scala tympani. As a result of this increase in length, the basilar membrane and papilla are both extended, with the latter developing into the organ of Corti, while the lagena is now called the cochlear duct. All of these structures together constitute the cochlea.

In therian mammals, the lagena is extended still further, becoming a coiled structure (cochlea) in order to accommodate its length within the head. The organ of Corti also has a more complex structure in mammals than it does in other amniotes.

The arrangement of the inner ear in living amphibians is, in most respects, similar to that of reptiles. However, they often lack a basilar papilla, having instead an entirely separate set of sensory cells at the upper edge of the saccule, referred to as the papilla amphibiorum, which appear to have the same function.

Although many fish are capable of hearing, the lagena is, at best, a short diverticulum of the saccule, and appears to have no role in sensation of sound. Various clusters of hair cells within the inner ear may instead be responsible; for example, bony fish contain a sensory cluster called the macula neglecta in the utricle that may have this function. Although fish have neither an outer nor a middle ear, sound may still be transmitted to the inner ear through the bones of the skull, or by the swim bladder, parts of which often lie close by in the body.

Vestibular system
By comparison with the cochlear system, the vestibular system varies relatively little between the various groups of jawed vertebrates. The central part of the system consists of two chambers, the saccule and utricle, each of which includes one or two small clusters of sensory hair cells. All jawed vertebrates also possess three semicircular canals arising from the utricle, each with an ampulla containing sensory cells at one end.

An endolymphatic duct runs from the saccule up through the head and ending close to the brain. In cartilaginous fish, this duct actually opens onto the top of the head, and in some teleosts, it is simply blind-ending. In all other species, however, it ends in an endolymphatic sac. In many reptiles, fish, and amphibians this sac may reach considerable size. In amphibians the sacs from either side may fuse into a single structure, which often extends down the length of the body, parallel with the spinal canal.

The primitive lampreys and hagfish, however, have a simpler system. The inner ear in these species consists of a single vestibular chamber, although in lampreys, this is associated with a series of sacs lined by cilia. Lampreys have only two semicircular canals, with the horizontal canal being absent, while hagfish have only a single, vertical, canal.

Equilibrium
The inner ear is primarily responsible for balance, equilibrium and orientation in three-dimensional space. The inner ear can detect both static and dynamic equilibrium. Three semicircular ducts and two chambers, which contain the saccule and utricle, enable the body to detect any deviation from equilibrium. The macula sacculi detects vertical acceleration while the macula utriculi is responsible for horizontal acceleration. These microscopic structures possess stereocilia and one kinocilium which are located within the gelatinous otolithic membrane. The membrane is further weighted with otoliths. Movement of the stereocilia and kinocilium enable the hair cells of the saccula and utricle to detect motion. The semicircular ducts are responsible for detecting rotational movement.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Inner ear


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Middle ear

The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear).

The mammalian middle ear contains three ossicles (malleus, incus, and stapes), which transfer the vibrations of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear is also known as the tympanic cavity and is surrounded by the tympanic part of the temporal bone. The auditory tube (also known as the Eustachian tube or the pharyngotympanic tube) joins the tympanic cavity with the nasal cavity (nasopharynx), allowing pressure to equalize between the middle ear and throat.

The primary function of the middle ear is to efficiently transfer acoustic energy from compression waves in air to fluid–membrane waves within the cochlea.

Ossicles
The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. The ossicles were given their Latin names for their distinctive shapes; they are also referred to as the hammer, anvil, and stirrup, respectively. The ossicles directly couple sound energy from the eardrum to the oval window of the cochlea. While the stapes is present in all tetrapods, the malleus and incus evolved from lower and upper jaw bones present in reptiles.

The ossicles are classically supposed to mechanically convert the vibrations of the eardrum into amplified pressure waves in the fluid of the cochlea (or inner ear), with a lever arm factor of 1.3. Since the effective vibratory area of the eardrum is about 14 fold larger than that of the oval window, the sound pressure is concentrated, leading to a pressure gain of at least 18.1. The eardrum is merged to the malleus, which connects to the incus, which in turn connects to the stapes. Vibrations of the stapes footplate introduce pressure waves in the inner ear. There is a steadily increasing body of evidence that shows that the lever arm ratio is actually variable, depending on frequency. Between 0.1 and 1 kHz it is approximately 2, it then rises to around 5 at 2 kHz and then falls off steadily above this frequency. The measurement of this lever arm ratio is also somewhat complicated by the fact that the ratio is generally given in relation to the tip of the malleus (also known as the umbo) and the level of the middle of the stapes. The eardrum is actually attached to the malleus handle over about a 0.5 cm distance. In addition, the eardrum itself moves in a very chaotic fashion at frequencies >3 kHz. The linear attachment of the eardrum to the malleus actually smooths out this chaotic motion and allows the ear to respond linearly over a wider frequency range than a point attachment. The auditory ossicles can also reduce sound pressure (the inner ear is very sensitive to overstimulation), by uncoupling each other through particular muscles.

The middle ear efficiency peaks at a frequency of around 1 kHz. The combined transfer function of the outer ear and middle ear gives humans a peak sensitivity to frequencies between 1 kHz and 3 kHz.

Muscles
The movement of the ossicles may be stiffened by two muscles. The stapedius muscle, the smallest skeletal muscle in the body, connects to the stapes and is controlled by the facial nerve; the tensor tympani muscle is attached to the upper end of the medial surface of the handle of malleus and is under the control of the medial pterygoid nerve which is a branch of the mandibular nerve of the trigeminal nerve. These muscles contract in response to loud sounds, thereby reducing the transmission of sound to the inner ear. This is called the acoustic reflex.

Nerves
Of surgical importance are two branches of the facial nerve that also pass through the middle ear space. These are the horizontal portion of the facial nerve and the chorda tympani. Damage to the horizontal branch during ear surgery can lead to paralysis of the face (same side of the face as the ear). The chorda tympani is the branch of the facial nerve that carries taste from the ipsilateral half (same side) of the tongue.

Sound transfer
Ordinarily, when sound waves in air strike liquid, most of the energy is reflected off the surface of the liquid. The middle ear allows the impedance matching of sound traveling in air to acoustic waves traveling in a system of fluids and membranes in the inner ear. This system should not be confused, however, with the propagation of sound as compression waves in liquid.

The acoustic impedance of air is about $$Z_1 = 400 \;\mathrm{Pa\cdot s /m}$$, while the impedance of cochlear fluids ($$Z_2 = 1.5 \times 10^6 \;\mathrm{Pa\cdot s /m}$$) is approximately equal to that of sea water. Because of this high impedance, only $$\frac{2Z_1}{Z_1 + Z_2} = 0.05%$$ of incident energy could be directly transmitted from the air to cochlear fluids.

The middle ear's impedance matching mechanism increases the efficiency of sound transmission. Two processes are involved:

 * Area Ratio: The area of the tympanic membrane is about 20 times larger than that of the stapes footplate in the cochlea. The forces collected over the eardrum are concentrated over a smaller area, thus increasing the pressure over the oval window.
 * Lever: The malleus is 1.3 times longer than the incus.

Together, they amplify pressure by 26 times, or about 30 dB. The actual value is around 20 dB across 200 to 10000 Hz.

The middle ear couples sound from air to the fluid via the oval window, using the principle of "mechanical advantage" in the form of the "hydraulic principle" and the "lever principle". The vibratory portion of the tympanic membrane (eardrum) is many times the surface area of the footplate of the stapes (the third ossicular bone which attaches to the oval window); furthermore, the shape of the articulated ossicular chain is a complex lever, the long arm being the long process of the malleus, the fulcrum being the body of the incus, and the short arm being the lenticular process of the incus. The collected pressure of sound vibration that strikes the tympanic membrane is therefore concentrated down to this much smaller area of the footplate, increasing the force but reducing the velocity and displacement, and thereby coupling the acoustic energy.

The middle ear is able to dampen sound conduction substantially when faced with very loud sound, by noise-induced reflex contraction of the middle-ear muscles.

Clinical significance
The middle ear is hollow in the tympanic cavity and Eustachian tube. In a high-altitude environment or on diving into water, there will be a pressure difference between the middle ear and the outside environment. This pressure will pose a risk of bursting or otherwise damaging the tympanum (eardrum) if it is not relieved. If middle ear pressure remains low, the eardrum (tympanic membrane) may become retracted into the middle ear. One of the functions of the Eustachian tubes that connect the middle ear to the nasopharynx is to help keep middle ear pressure the same as air pressure. The Eustachian tubes are normally pinched off at the nose end, to prevent being clogged with mucus, but they may be opened by lowering and protruding the jaw; this is why yawning or chewing helps relieve the pressure felt in the ears when on board an aircraft. Eustachian tube obstruction may result in fluid build up in the middle ear, which causes a conductive hearing loss. Otitis media is an inflammation of the middle ear.

Injuries
The middle ear is well protected from most minor external injuries by its internal location, but is vulnerable to pressure injury (barotrauma).

Infections
Recent findings indicate that the middle ear mucosa could be subjected to human papillomavirus infection. Indeed, DNAs belonging to oncogenic HPVs, i.e., HPV16 and HPV18, have been detected in normal middle ear specimens, thereby indicating that the normal middle ear mucosa could potentially be a target tissue for HPV infection.

Inflammation of the middle ear, also known as otitis media, is a prevalent condition, especially among infants under six months old. This ailment occurs when the middle ear, typically filled with air, becomes infected or obstructed by fluid behind the eardrum. In certain cases, a surgical intervention called myringotomy and tube insertion may be necessary to alleviate the symptoms and complications associated with this condition. The risk of otitis media can be mitigated through various preventive measures, such as receiving pneumococca l and influenza vaccines, breastfeeding infants, and avoiding secondhand smoke. Furthermore, the use of analgesics plays a vital role in alleviating the pain caused by acute otitis media.

Diversity and evolution
The middle ear of tetrapods is analogous with the spiracle of fishes, an opening from the pharynx to the side of the head in front of the main gill slits. In fish embryos, the spiracle forms as a pouch in the pharynx, which grows outward and breaches the skin to form an opening; in most tetrapods, this breach is never quite completed, and the final vestige of tissue separating it from the outside world becomes the eardrum. The inner part of the spiracle, still connected to the pharynx, forms the eustachian tube.

In reptiles, birds, and early fossil tetrapods, there is a single auditory ossicle, the columella which is homologous with the stapes, or "stirrup" of mammals. This is connected indirectly with the eardrum via a mostly cartilaginous extracolumella and medially to the inner-ear spaces via a widened footplate in the fenestra ovalis. The columella is an evolutionary derivative of the bone known as the hyomandibula in fish ancestors, a bone that supported the skull and braincase.

Amphibians
The structure of the middle ear in living amphibians varies considerably and is often degenerate. In most frogs and toads, it is similar to that of reptiles, but in other amphibians, the middle ear cavity is often absent. In these cases, the stapes either is also missing or, in the absence of an eardrum, connects to the quadrate bone in the skull, although, it is presumed, it still has some ability to transmit vibrations to the inner ear. In many amphibians, there is also a second auditory ossicle, the operculum (not to be confused with the structure of the same name in fishes). This is a flat, plate-like bone, overlying the fenestra ovalis, and connecting it either to the stapes or, via a special muscle, to the scapula. It is not found in any other vertebrates.

Mammals
Mammals are unique in having evolved a three-ossicle middle-ear independently of the various single-ossicle middle ears of other land vertebrates, all during the Triassic period of geological history. Functionally, the mammalian middle ear is very similar to the single-ossicle ear of non-mammals, except that it responds to sounds of higher frequency, because these are better taken up by the inner ear (which also responds to higher frequencies than those of non-mammals). The malleus, or "hammer", evolved from the articular bone of the lower jaw, and the incus, or "anvil", from the quadrate. In other vertebrates, these bones form the primary jaw joint, but the expansion of the dentary bone in mammals led to the evolution of an entirely new jaw joint, freeing up the old joint to become part of the ear. For a period of time, both jaw joints existed together, one medially and one laterally. The evolutionary process leading to a three-ossicle middle ear was thus an "accidental" byproduct of the simultaneous evolution of the new, secondary jaw joint. In many mammals, the middle ear also becomes protected within a cavity, the auditory bulla, not found in other vertebrates. A bulla evolved late in time and independently numerous times in different mammalian clades, and it can be surrounded by membranes, cartilage or bone. The bulla in humans is part of the temporal bone.

Recently found fossils such as Morganucodon show intermediary steps of middle ear evolution. A new morganucodontan-like species, Dianoconodon youngi, shows parts of the mandible (= dentary) that permit an auditory function, although these bones are still attached to the mandible.

title: Middle ear


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Outer ear

The outer ear, external ear, or auris externa is the external part of the ear, which consists of the auricle (also pinna) and the ear canal. It gathers sound energy and focuses it on the eardrum (tympanic membrane).

Auricle
The visible part is called the auricle, also known as the pinna, especially in other animals. It is composed of a thin plate of yellow elastic cartilage, covered with integument, and connected to the surrounding parts by ligaments and muscles; and to the commencement of the ear canal by fibrous tissue. Many mammals can move the pinna (with the auriculares muscles) in order to focus their hearing in a certain direction in much the same way that they can turn their eyes. Most humans do not have this ability.

Ear canal
From the pinna, the sound waves move into the ear canal (also known as the external acoustic meatus) a simple tube running through to the middle ear. This tube leads inward from the bottom of the auricula and conducts the vibrations to the tympanic cavity and amplifies frequencies in the range 3 kHz to 12 kHz.

Intrinsic muscles
The intrinsic auricular muscles are:
 * The helicis major is a narrow vertical band situated upon the anterior margin of the helix. It arises below, from the spina helicis, and is inserted into the anterior border of the helix, just where it is about to curve backward.
 * The helicis minor is an oblique fasciculus, covering the crus helicis.
 * The tragicus is a short, flattened vertical band on the lateral surface of the tragus. Also known as the mini lobe.
 * The antitragicus arises from the outer part of the antitragus, and is inserted into the cauda helicis and antihelix.
 * The transverse muscle is placed on the cranial surface of the pinna. It consists of scattered fibers, partly tendinous and partly muscular, extending from the eminentia conchae to the prominence corresponding with the scapha.
 * The oblique muscle also on the cranial surface, consists of a few fibers extending from the upper and back part of the concha to the convexity immediately above it.

The intrinsic muscles contribute to the topography of the auricle, while also function as a sphincter of the external auditory meatus. It has been suggested that during prenatal development in the womb, these muscles exert forces on the cartilage which in turn affects the shaping of the ear.

Extrinsic muscles
The extrinsic auricular muscles are the three muscles surrounding the auricula or outer ear:
 * anterior auricular muscle
 * superior auricular muscle
 * posterior auricular muscle

The superior muscle is the largest of the three, followed by the posterior and the anterior.

In some mammals these muscles can adjust the direction of the pinna. In humans these muscles possess very little action. The auricularis anterior draws the auricula forward and upward, the auricularis superior slightly raises it, and the auricularis posterior draws it backward. The superior auricular muscle also acts as a stabilizer of the occipitofrontalis muscle and as a weak brow lifter. The presence of auriculomotor activity in the posterior auricular muscle causes the muscle to contract and cause the pinna to be pulled backwards and flatten when exposed to sudden, surprising sounds.

Function
One consequence of the configuration of the outer ear is selectively to boost the sound pressure 30- to 100-fold for frequencies around 3 kHz. This amplification makes humans most sensitive to frequencies in this range—and also explains why they are particularly prone to acoustical injury and hearing loss near this frequency. Most human speech sounds are also distributed in the bandwidth around 3 kHz.

Clinical significance
Malformations of the external ear can be a consequence of hereditary disease, or exposure to environmental factors such as radiation, infection. Such defects include:
 * A preauricular fistula, which is a long narrow tube, usually near the tragus. This can be inherited as an autosomal recessive fashion and may suffer from chronic infection in later life.
 * Cosmetic defects, such as very large ears, small ears.
 * Malformation that may lead to functional impairment, such as atresia of the external auditory meatus or aplasia of the pinna,
 * Genetic syndromes, which include:
 * Konigsmark syndrome, characterised by small ears and atresia of the external auditory canal, causing conductive hearing loss and inherited in an autosomal recessive manner.
 * Goldenhar syndrome, a combination of developmental abnormalities affecting the ears, eyes, bones of the skull, and vertebrae, inherited in an autosomal dominant manner.
 * Treacher Collins syndrome, characterised by dysplasia of the auricle, atresia of the bony part of the auditory canal, hypoplasia of the auditory ossicles and tympanic cavity, and 'mixed' deafness (both sensorineural and conductive), inherited in an autosomal dominant manner.
 * Crouzon syndrome, characterised by bilateral atresia of the external auditory canal, inherited in an autosomal dominant manner.

Surgery
Usually, malformations are treated with surgery, although artificial prostheses are also sometimes used. If malformations are accompanied by hearing loss amenable to correction, then the early use of hearing aids may prevent complete hearing loss.
 * Preauricular fistulas are generally not treated unless chronically inflamed.
 * Cosmetic defects without functional impairment are generally repaired after ages 6–7.

title: Outer ear


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Federal Communications Commission

The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdiction over the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, and homeland security.

The FCC was formed by the Communications Act of 1934 to replace the radio regulation functions of the previous Federal Radio Commission. The FCC took over wire communication regulation from the Interstate Commerce Commission. The FCC's mandated jurisdiction covers the 50 states, the District of Columbia, and the territories of the United States. The FCC also provides varied degrees of cooperation, oversight, and leadership for similar communications bodies in other countries in North America. The FCC is funded entirely by regulatory fees. It has an estimated fiscal-2022 budget of US $388 million. It has 1,482 federal employees as of July 2020.

Mission and agency objectives
The FCC's mission, specified in Section One of the Communications Act of 1934 and amended by the Telecommunications Act of 1996 (amendment to 47 U.S.C. §151), is to "make available so far as possible, to all the people of the United States, without discrimination on the basis of race, color, religion, national origin, or sex, rapid, efficient, nationwide, and world-wide wire and radio communication services with adequate facilities at reasonable charges."

The act furthermore provides that the FCC was created "for the purpose of the national defense" and "for the purpose of promoting safety of life and property through the use of wire and radio communications."

Consistent with the objectives of the act as well as the 1999 Government Performance and Results Act (GPRA), the FCC has identified four goals in its 2018–22 Strategic Plan. They are: Closing the Digital Divide, Promoting Innovation, Protecting Consumers & Public Safety, and Reforming the FCC's Processes.

Commissioners
The FCC is directed by five commissioners appointed by the president of the United States and confirmed by the United States Senate for five-year terms, except when filling an unexpired term. The U.S. president designates one of the commissioners to serve as chairman. No more than three commissioners may be members of the same political party. None of them may have a financial interest in any FCC-related business.

Commissioners may continue serving until the appointment of their replacements. However, they may not serve beyond the end of the next session of Congress following term expiration. In practice, this means that commissioners may serve up to $1 1/2$ years beyond the official term expiration listed above if no replacement is appointed. This would end on the date that Congress adjourns its annual session, generally no later than noon on January 3.

Bureaus
The FCC is organized into seven bureaus, each headed by a "chief" that is appointed by the chair of the commission. Bureaus process applications for licenses and other filings, analyze complaints, conduct investigations, develop and implement regulations, and participate in hearings.
 * The Consumer & Governmental Affairs Bureau (CGB) develops and implements the FCC's consumer policies, including disability access. CGB serves as the public face of the FCC through outreach and education, as well as through its Consumer Center, which is responsible for responding to consumer inquiries and complaints. CGB also maintains collaborative partnerships with state, local, and tribal governments in such areas as emergency preparedness and implementation of new technologies.
 * The Enforcement Bureau (EB) is responsible for enforcement of provisions of the Communications Act 1934, FCC rules, FCC orders, and terms and conditions of station authorizations. Major areas of enforcement that are handled by the Enforcement Bureau are consumer protection, local competition, public safety, and homeland security.
 * The Media Bureau (MB) develops, recommends and administers the policy and licensing programs relating to electronic media, including cable television, broadcast television, and radio in the United States and its territories. The Media Bureau also handles post-licensing matters regarding direct broadcast satellite service.
 * The Space Bureau (SB) leads policy and licensing matters related to satellite and space-based communications and activities. It will also serve as the commission's liaison to other agencies engaged in space policy. It was created in April 2023 after the former International Bureau (IB) and its functions were divided between the Space Bureau and a new Office of International Affairs.
 * The Wireless Telecommunications Bureau regulates domestic wireless telecommunications programs and policies, including licensing. The bureau also implements competitive bidding for spectrum auctions and regulates wireless communications services including mobile phones, public safety, and other commercial and private radio services.
 * The Wireline Competition Bureau (WCB) develops policy concerning wire line telecommunications. The Wireline Competition Bureau's main objective is to promote growth and economical investments in wireline technology infrastructure, development, markets, and services.
 * The Public Safety and Homeland Security Bureau was launched in 2006 with a focus on critical communications infrastructure.

Offices
The FCC has twelve staff offices. The FCC's offices provide support services to the bureaus.
 * The Office of Administrative Law Judges (OALJ) is responsible for conducting hearings ordered by the commission. The hearing function includes acting on interlocutory requests filed in the proceedings such as petitions to intervene, petitions to enlarge issues, and contested discovery requests. An administrative law judge, appointed under the Administrative Procedure Act, presides at the hearing during which documents and sworn testimony are received in evidence, and witnesses are cross-examined. At the conclusion of the evidentiary phase of a proceeding, the presiding administrative law judge writes and issues an initial decision that may be appealed to the commission.
 * The Office of Communications Business Opportunities (OCBO) promotes telecommunications business opportunities for small, minority-owned, and women-owned businesses. OCBO works with entrepreneurs, industry, public interest organizations, individuals, and others to provide information about FCC policies, increase ownership and employment opportunities, foster a diversity of voices and viewpoints over the airwaves, and encourage participation in FCC proceedings.
 * The Office of Economics and Analytics (OEA) is responsible for expanding and deepening the use of economic analysis into Commission policy making, for enhancing the development and use of auctions, and for implementing consistent and effective agency wide-data practices and policies. It was created in 2018 by merging staff from the now defunct Office of Strategic Planning & Policy Analysis with economists dispersed throughout various other offices.
 * The Office of Engineering and Technology (OET) advises the commission concerning engineering matters.
 * Its chief role is to manage the electromagnetic spectrum, specifically frequency allocation and spectrum usage. OET conducts technical studies of advanced phases of terrestrial and space communications and administers FCC rules regarding radio devices, experimental radio services, and industrial, scientific, and medical equipment.
 * OET organizes the Technical Advisory Council, a committee of FCC advisors from major telecommunication and media corporations.
 * OET operates the Equipment Authorization Branch, which has the task of overseeing equipment authorization for all devices using the electromagnetic energy from 9 kHz to 300 GHz. OET maintains an electronic database of all Certified equipment that can be easily accessed by the public.
 * The Office of General Counsel serves as the chief legal adviser to the commission. The general counsel also represents the commission in litigation in United States federal courts, recommends decisions in adjudicatory matters before the commission, assists the commission in its decision-making capacity and performs a variety of legal functions regarding internal and other administrative matters.
 * The Office of the Inspector General (OIG) recommends policies to prevent fraud in agency operations. The inspector general recommends corrective action where appropriate, referring criminal matters to the United States Department of Justice for potential prosecution.
 * The Office of International Affairs (OIA) is responsible for the commission's engagement in foreign and international regulatory authorities, including multilateral and regional organizations. OIA will also facilitate through rulemaking and licensing the commission's development of policies regarding international telecommunications facilities and services as well as submarine cables, and advise the commission on foreign ownership issues.
 * The Office of Legislative Affairs (OLA) is the FCC's liaison to the United States Congress, providing lawmakers with information about FCC regulations. OLA also prepares FCC witnesses for congressional hearings, and helps create FCC responses to legislative proposals and congressional inquiries. In addition, OLA is a liaison to other federal agencies, as well as state and local governments.
 * The Office of the Managing Director (OMD) is responsible for the administration and management of the FCC, including the agency's budget, personnel, security, contracts, and publications.
 * The Office of Media Relations (OMR) is responsible for the dissemination of commission announcements, orders, proceedings, and other information per media requests. OMR manages the FCC Daily Digest, website, and Audio Visual Center.
 * The Office of the Secretary (OSEC) oversees the receipt and distribution of documents filed by the public through electronic and paper filing systems and the FCC Library collection. In addition, OSEC publishes legal notices of commission decisions in the Federal Register and the FCC Record.
 * The Office of Workplace Diversity (OWD) develops policy to provide a full and fair opportunity for all employees, regardless of non-merit factors such as race, religion, gender, color, age, disability, sexual orientation or national origin, to carry out their duties in the workplace free from unlawful discriminatory treatment, including sexual harassment and retaliation for engaging in legally protected activities.

Headquarters
The FCC leases space in the Sentinel Square III building in northeast Washington, D.C.

Prior to moving to its new headquarters in October 2020, the FCC leased space in the Portals building in southwest Washington, D.C. Construction of the Portals building was scheduled to begin on March 1, 1996. In January 1996, the General Services Administration signed a lease with the building's owners, agreeing to let the FCC lease 450000 sqft of space in Portals for 20 years, at a cost of $17.3 million per year in 1996 dollars. Prior to the Portals, the FCC had space in six buildings at and around 19th Street NW and M Street NW. The FCC first solicited bids for a new headquarters complex in 1989. In 1991 the GSA selected the Portals site. The FCC had wanted to move into a more expensive area along Pennsylvania Avenue.

Communications Act of 1934
In 1934, Congress passed the Communications Act, which abolished the Federal Radio Commission and transferred jurisdiction over radio licensing to a new Federal Communications Commission, including in it also the telecommunications jurisdiction previously handled by the Interstate Commerce Commission.

Title II of the Communications Act focused on telecommunications using many concepts borrowed from railroad legislation and Title III contained provisions very similar to the Radio Act of 1927.

The initial organization of the FCC was effected July 17, 1934, in three divisions, Broadcasting, Telegraph, and Telephone. Each division was led by two of the seven commissioners, with the FCC chairman being a member of each division. The organizing meeting directed the divisions to meet on July 18, July 19, and July 20, respectively.

Report on Chain Broadcasting
In 1940, the Federal Communications Commission issued the "Report on Chain Broadcasting" which was led by new FCC chairman James Lawrence Fly (and Telford Taylor as general counsel). The major point in the report was the breakup of the National Broadcasting Company (NBC), which ultimately led to the creation of the American Broadcasting Company (ABC), but there were two other important points. One was network option time, the culprit here being the Columbia Broadcasting System (CBS). The report limited the amount of time during the day and at what times the networks may broadcast. Previously a network could demand any time it wanted from a Network affiliate. The second concerned artist bureaus. The networks served as both agents and employers of artists, which was a conflict of interest the report rectified.

Freeze of 1948
In assigning television stations to various cities after World War II, the FCC found that it placed many stations too close to each other, resulting in interference. At the same time, it became clear that the designated VHF channels, 2 through 13, were inadequate for nationwide television service. As a result, the FCC stopped giving out construction permits for new licenses in October 1948, under the direction of Chairman Rosel H. Hyde. Most expected this "Freeze" to last six months, but as the allocation of channels to the emerging UHF technology and the eagerly awaited possibilities of color television were debated, the FCC's re-allocation map of stations did not come until April 1952, with July 1, 1952, as the official beginning of licensing new stations.

Other FCC actions hurt the fledgling DuMont and ABC networks. American Telephone and Telegraph (AT&T) forced television coaxial cable users to rent additional radio long lines, discriminating against DuMont, which had no radio network operation. DuMont and ABC protested AT&T's television policies to the FCC, which regulated AT&T's long-line charges, but the commission took no action. The result was that financially marginal DuMont was spending as much in long-line charge as CBS or NBC while using only about 10 to 15 percent of the time and mileage of either larger network.

The FCC's "Sixth Report & Order" ended the Freeze. It took five years for the US to grow from 108 stations to more than 550. New stations came on line slowly, only five by the end of November 1952. The Sixth Report and Order required some existing television stations to change channels, but only a few existing VHF stations were required to move to UHF, and a handful of VHF channels were deleted altogether in smaller media markets like Peoria, Fresno, Bakersfield and Fort Wayne, Indiana to create markets which were UHF "islands." The report also set aside a number of channels for the newly emerging field of educational television, which hindered struggling ABC and DuMont's quest for affiliates in the more desirable markets where VHF channels were reserved for non-commercial use.

The Sixth Report and Order also provided for the "intermixture" of VHF and UHF channels in most markets; UHF transmitters in the 1950s were not yet powerful enough, nor receivers sensitive enough (if they included UHF tuners at all - they were not formally required until the 1960s All-Channel Receiver Act), to make UHF viable against entrenched VHF stations. In markets where there were no VHF stations and UHF was the only TV service available, UHF survived. In other markets, which were too small to financially support a television station, too close to VHF outlets in nearby cities, or where UHF was forced to compete with more than one well-established VHF station, UHF had little chance for success.

Denver had been the largest U.S. city without a TV station by 1952. Senator Edwin Johnson (D-Colorado), chair of the Senate's Interstate and Foreign Commerce Committee, had made it his personal mission to make Denver the first post-Freeze station. The senator had pressured the FCC, and proved ultimately successful as the first new station (a VHF station) came on-line a remarkable ten days after the commission formally announced the first post-Freeze construction permits. KFEL (now KWGN-TV)'s first regular telecast was on July 21, 1952.

Telecommunications Act of 1996
In 1996, Congress enacted the Telecommunications Act of 1996, in the wake of the breakup of AT&T resulting from the U.S. Department of Justice's antitrust suit against AT&T. The legislation attempted to create more competition in local telephone service by requiring Incumbent Local Exchange Carriers to provide access to their facilities for Competitive Local Exchange Carriers. This policy has thus far had limited success and much criticism.

The development of the Internet, cable services and wireless services has raised questions whether new legislative initiatives are needed as to competition in what has come to be called 'broadband' services. Congress has monitored developments but as of 2009 has not undertaken a major revision of applicable regulation. The Local Community Radio Act in the 111th Congress has gotten out of committee and will go before the house floor with bi-partisan support, and unanimous support of the FCC.

By passing the Telecommunications Act of 1996, Congress also eliminated the cap on the number of radio stations any one entity could own nationwide and also substantially loosened local radio station ownership restrictions. Substantial radio consolidation followed. Restrictions on ownership of television stations were also loosened. Public comments to the FCC indicated that the public largely believed that the severe consolidation of media ownership had resulted in harm to diversity, localism, and competition in media, and was harmful to the public interest.

Modernization of the FCC's information technology systems
David A. Bray joined the commission in 2013 as chief information officer and quickly announced goals of modernizing the FCC's legacy information technology (IT) systems, citing 200 different systems for only 1750 people a situation he found "perplexing". These efforts later were documented in a 2015 Harvard Case Study. In 2017, Christine Calvosa replaced Bray as the acting CIO of FCC.

2023 reorganization and Space Bureau establishment
On January 4, 2023, the FCC voted unanimously to create a newly-formed Space Bureau and Office of International Affairs within the agency, replacing the existing International Bureau. FCC chairwoman Jessica Rosenworcel explained that the move was done to improve the FCC's "coordination across the federal government" and to "support the 21st-century satellite industry." The decision to establish the Space Bureau was reportedly done to improve the agency's capacity to regulate Satellite Internet access. The new bureau officially launched on April 11, 2023.

Commissioners
The commissioners of the FCC are:

The initial group of FCC commissioners after establishment of the commission in 1934 comprised the following seven members:

The complete list of commissioners is available on the FCC website. Frieda B. Hennock (D-NY) was the first female commissioner of the FCC in 1948.

Broadcast radio and television
The FCC regulates broadcast stations, repeater stations as well as commercial broadcasting operators who operate and repair certain radiotelephone, radio and television stations. Broadcast licenses are to be renewed if the station meets the "public interest, convenience, or necessity". The FCC's enforcement powers include fines and broadcast license revocation (see FCC MB Docket 04-232). Burden of proof would be on the complainant in a petition to deny.

Cable and satellite
The FCC first promulgated rules for cable television in 1965, with cable and satellite television now regulated by the FCC under Title VI of the Communications Act. Congress added Title VI in the Cable Communications Policy Act of 1984, and made substantial modifications to Title VI in the Cable Television and Consumer Protection and Competition Act of 1992. Further modifications to promote cross-modal competition (telephone, video, etc.) were made in the Telecommunications Act of 1996, leading to the current regulatory structure.

Content regulation and indecency
Broadcast television and radio stations are subject to FCC regulations including restrictions against indecency or obscenity. The Supreme Court has repeatedly held, beginning soon after the passage of the Communications Act of 1934, that the inherent scarcity of radio spectrum allows the government to impose some types of content restrictions on broadcast license holders notwithstanding the First Amendment. Cable and satellite providers are also subject to some content regulations under Title VI of the Communications Act such as the prohibition on obscenity, although the limitations are not as restrictive compared to broadcast stations.

The 1981 inauguration of Ronald Reagan as President of the United States accelerated an already ongoing shift in the FCC towards a decidedly more market-oriented stance. A number of regulations felt to be outdated were removed, most controversially the Fairness Doctrine in 1987.

In terms of indecency fines, there was no action taken by the FCC on the case FCC v. Pacifica until 1987, about ten years after the landmark United States Supreme Court decision that defined the power of the FCC over indecent material as applied to broadcasting.

After the 1990s had passed, the FCC began to increase its censorship and enforcement of indecency regulations in the early 2000s to include a response to the Janet Jackson "wardrobe malfunction" that occurred during the halftime show of Super Bowl XXXVIII.

Then on June 15, 2006, President George W. Bush signed into law the Broadcast Decency Enforcement Act of 2005 sponsored by then-senator Sam Brownback, a former broadcaster himself, and endorsed by Congressman Fred Upton of Michigan who authored a similar bill in the United States House of Representatives. The new law stiffens the penalties for each violation of the Act. The Federal Communications Commission will be able to impose fines in the amount of $325,000 for each violation by each station that violates decency standards. The legislation raised the fine ten times over the previous maximum of $32,500 per violation.

Media ownership
The FCC has established rules limiting the national share of media ownership of broadcast radio or television stations. It has also established cross-ownership rules limiting ownership of a newspaper and broadcast station in the same market, in order to ensure a diversity of viewpoints in each market and serve the needs of each local market.

Diversity
In the second half of 2006, groups such as the National Hispanic Media Coalition, the National Latino Media Council, the National Association of Hispanic Journalists, the National Institute for Latino Policy, the League of United Latin American Citizens (LULAC) and others held town hall meetings in California, New York and Texas on media diversity as its effects Latinos and minority communities. They documented widespread and deeply felt community concerns about the negative effects of media concentration and consolidation on racial-ethnic diversity in staffing and programming. At these Latino town hall meetings, the issue of the FCC's lax monitoring of obscene and pornographic material in Spanish-language radio and the lack of racial and national-origin diversity among Latino staff in Spanish-language television were other major themes.

President Barack Obama appointed Mark Lloyd to the FCC in the newly created post of associate general counsel/chief diversity officer.

Localism
Numerous controversies have surrounded the city of license concept as the internet has made it possible to broadcast a single signal to every owned station in the nation at once, particularly when Clear Channel, now IHeartMedia, became the largest FM broadcasting corporation in the US after the Telecommunications Act of 1996 became law - owning over 1,200 stations at its peak. As part of its license to buy more radio stations, Clear Channel was forced to divest all TV stations.

Digital television transition
To facilitate the adoption of digital television, the FCC issued a second digital TV (DTV) channel to each holder of an analog TV station license. All stations were required to buy and install all new equipment (transmitters, TV antennas, and even entirely new broadcast towers), and operate for years on both channels. Each licensee was required to return one of their two channels following the end of the digital television transition.

After delaying the original deadlines of 2006, 2008, and eventually February 17, 2009, on concerns about elderly and rural folk, on June 12, 2009, all full-power analog terrestrial TV licenses in the U.S. were terminated as part of the DTV transition, leaving terrestrial television available only from digital channels and a few low-power LPTV stations. To help U.S. consumers through the conversion, Congress established a federally sponsored DTV Converter Box Coupon Program for two free converters per household.

Wireline policy
The FCC regulates telecommunications services under Title II of the Communications Act of 1934. Title II imposes common carrier regulation under which carriers offering their services to the general public must provide services to all customers and may not discriminate based on the identity of the customer or the content of the communication. This is similar to and adapted from the regulation of transportation providers (railroad, airline, shipping, etc.) and some public utilities. Wireless carriers providing telecommunications services are also generally subject to Title II regulation except as exempted by the FCC.

Telephone
The FCC regulates interstate telephone services under Title II. The Telecommunications Act of 1996 was the first major legislative reform since the 1934 act and took several steps to de-regulate the telephone market and promote competition in both the local and long-distance marketplace.

From monopoly to competition
The important relationship of the FCC and the American Telephone and Telegraph (AT&T) Company evolved over the decades. For many years, the FCC and state officials agreed to regulate the telephone system as a natural monopoly. The FCC controlled telephone rates and imposed other restrictions under Title II to limit the profits of AT&T and ensure nondiscriminatory pricing.

In the 1960s, the FCC began allowing other long-distance companies, namely MCI, to offer specialized services. In the 1970s, the FCC allowed other companies to expand offerings to the public. A lawsuit in 1982 led by the Justice Department after AT&T underpriced other companies, resulted in the breakup of the Bell System from AT&T. Beginning in 1984, the FCC implemented a new goal that all long-distance companies had equal access to the local phone companies' customers. Effective January 1, 1984, the Bell System's many member-companies were variously merged into seven independent "Regional Holding Companies", also known as Regional Bell Operating Companies (RBOCs), or "Baby Bells". This divestiture reduced the book value of AT&T by approximately 70%.

Internet
The FCC initially exempted "information services" such as broadband Internet access from regulation under Title II. The FCC held that information services were distinct from telecommunications services that are subject to common carrier regulation.

However, Section 706 of the Telecommunications Act of 1996 required the FCC to help accelerate deployment of "advanced telecommunications capability" which included high-quality voice, data, graphics, and video, and to regularly assess its availability. In August 2015, the FCC said that nearly 55 million Americans did not have access to broadband capable of delivering high-quality voice, data, graphics and video offerings.

On February 26, 2015, the FCC reclassified broadband Internet access as a telecommunications service, thus subjecting it to Title II regulation, although several exemptions were also created. The reclassification was done in order to give the FCC a legal basis for imposing net neutrality rules (see below), after earlier attempts to impose such rules on an "information service" had been overturned in court.

Net neutrality
In 2005, the FCC formally established the following principles: To encourage broadband deployment and preserve and promote the open and interconnected nature of the public Internet, Consumers are entitled to access the lawful Internet content of their choice; Consumers are entitled to run applications and use services of their choice, subject to the needs of law enforcement; Consumers are entitled to connect their choice of legal devices that do not harm the network; Consumers are entitled to competition among network providers, application and service providers, and content providers. However, broadband providers were permitted to engage in "reasonable network management."

On August 1, 2008, the FCC formally voted 3-to-2 to uphold a complaint against Comcast, the largest cable company in the US, ruling that it had illegally inhibited users of its high-speed Internet service from using file-sharing software. The FCC imposed no fine, but required Comcast to end such blocking in 2008. FCC chairman Kevin J. Martin said the order was meant to set a precedent that Internet providers, and indeed all communications companies, could not prevent customers from using their networks the way they see fit unless there is a good reason. In an interview Martin stated that "We are preserving the open character of the Internet" and "We are saying that network operators can't block people from getting access to any content and any applications." Martin's successor, Julius Genachowski has maintained that the FCC has no plans to regulate the internet, saying: "I've been clear repeatedly that we're not going to regulate the Internet." The Comcast case highlighted broader issues of whether new legislation is needed to force Internet providers to maintain net neutrality, i.e. treat all uses of their networks equally. The legal complaint against Comcast related to BitTorrent, software that is commonly used for downloading larger files.

In December 2010, the FCC revised the principles from the original Internet policy statement and adopted the Open Internet Order consisting of three rules regarding the Internet: Transparency. Fixed and mobile broadband providers must disclose the network management practices, performance characteristics, and terms and conditions of their broadband services; No blocking. Fixed broadband providers may not block lawful content, applications, services, or non-harmful devices; mobile broadband providers may not block lawful websites, or block applications that compete with their voice or video telephony services; and No unreasonable discrimination.

On January 14, 2014, Verizon won their lawsuit over the FCC in the United States Court of Appeals for the District of Columbia Court. Verizon was suing over increased regulation on internet service providers on the grounds that "even though the commission has general authority to regulate in this arena, it may not impose requirements that contravene express statutory mandates. Given that the commission has chosen to classify broadband providers in a manner that exempts them from treatment as common carriers, the Communications Act expressly prohibits the commission from nonetheless regulating them as such."

After these setbacks in court, in April 2014 the FCC issued a Notice of Proposed Rulemaking regarding a path forward for The Open Internet Order. On November 10, 2014, President Obama created a YouTube video recommending that the FCC reclassify broadband Internet service as a telecommunications service in order to preserve net neutrality.

On February 26, 2015, the FCC ruled in favor of net neutrality by applying Title II (common carrier) of the Communications Act of 1934 and Section 706 of the Telecommunications act of 1996 to the Internet.

The rules prompted debate about the applicability of First Amendment protections to Internet service providers and edge providers. Republican commissioner Ajit Pai said the Open Internet Order "posed a special danger" to "First Amendment speech, freedom of expression, [and] even freedom of association." Democratic member and then-Chairman Tom Wheeler said in response that the rules were "no more a plan to regulate the Internet than the First Amendment is a plan to regulate free speech. They both stand for the same concept." According to a Washington Post poll, 81% of Americans supported net neutrality in 2014, with 81% of Democrats and 85% of Republicans saying they opposed allowing Internet providers to charge websites for faster speeds.

On March 12, 2015, the FCC released the specific details of the net neutrality rules. On April 13, 2015, the FCC published the final rule on its new "Net Neutrality" regulations.

On April 27, 2017, FCC chairman Ajit Pai released a draft Notice of Proposed Rulemaking that would revise the legal foundation for the agency's Open Internet regulations. The NPRM was voted on at the May 18th Open Meeting. On December 14, the commission voted 3–2 in favor of passing the repeal of the 2015 rules. The repeal formally took effect on June 11, 2018, when the 2015 rules expired.

NSA wiretapping
When it emerged in 2006 that AT&T, BellSouth and Verizon may have broken U.S. laws by aiding the National Security Agency in possible illegal wiretapping of its customers, Congressional representatives called for an FCC investigation into whether or not those companies broke the law. The FCC declined to investigate, however, claiming that it could not investigate due to the classified nature of the program– a move that provoked the criticism of members of Congress.

"Today the watchdog agency that oversees the country's telecommunications industry refused to investigate the nation's largest phone companies' reported disclosure of phone records to the NSA", said Rep. Edward Markey (D-Mass.) in response to the decision. "The FCC, which oversees the protection of consumer privacy under the Communications Act of 1934, has taken a pass at investigating what is estimated to be the nation's largest violation of consumer privacy ever to occur. If the oversight body that monitors our nation's communications is stepping aside then Congress must step in."

Wireless policy
The FCC regulates all non-Federal uses of radio frequency spectrum in the United States under Title III of the Communications Act of 1934. In addition to over-the-air broadcast television and radio stations, this includes commercial mobile (i.e., mobile phone) services, amateur radio, citizen's band radio, theatrical wireless microphone installations, and a very wide variety of other services. Use of radio spectrum by U.S. federal government agencies is coordinated by the National Telecommunications and Information Administration, an agency within the Department of Commerce.

Commercial mobile service
Commercial mobile radio service (CMRS) providers, including all mobile phone carriers, are subject to spectrum and wireless regulations under Title III (similar to broadcasters) as well as common carrier regulations under Title II (similar to wireline telephone carriers), except as provided by the FCC.

Spectrum auctions
Beginning in 1994, the FCC has usually assigned commercial spectrum licenses through the use of competitive bidding, i.e., spectrum auctions. These auctions have raised tens of billions of dollars for the U.S. Treasury, and the FCC's auction approach is now widely emulated throughout the world. The FCC typically obtains spectrum for auction that has been reclaimed from other uses, such as spectrum returned by television broadcasters after the digital television transition, or spectrum made available by federal agencies able to shift their operations to other bands.

Unlicensed spectrum
Normally, any intentional radio transmission requires an FCC license pursuant to Title III. However, in recent decades the FCC has also opened some spectrum bands for unlicensed operations, typically restricting them to low power levels conducive to short-range applications. This has facilitated the development of a very wide range of common technologies from wireless garage door openers, cordless phones, and baby monitors to Wi-Fi and Bluetooth among others. However, unlicensed devices — like most radio transmission equipment — must still receive technical approval from the FCC before being sold into the marketplace, including ensuring that such devices cannot be modified by end users to increase transmit power above FCC limits.

White spaces
"White spaces" are radio frequencies that went unused after the federally mandated transformation of analog TV signals to digital. On October 15, 2008, FCC Chairman Kevin Martin announced his support for the unlicensed use of white spaces. Martin said he was "hoping to take advantage of utilizing these airwaves for broadband services to allow for unlicensed technologies and new innovations in that space."

Google, Microsoft and other companies are vying for the use of this white-space to support innovation in Wi-Fi technology. Broadcasters and wireless microphone manufacturers fear that the use of white space would "disrupt their broadcasts and the signals used in sports events and concerts." Cell phone providers such as T-Mobile US have mounted pressure on the FCC to instead offer up the white space for sale to boost competition and market leverage.

On November 4, 2008, the FCC commissioners unanimously agreed to open up unused broadcast TV spectrum for unlicensed use.

Amateur radio
Amateur radio operators in the United States must be licensed by the FCC before transmitting. While the FCC maintains control of the written testing standards, it no longer administers the exams, having delegated that function to private volunteer organizations. No amateur license class requires examination in Morse code; neither the FCC nor the volunteer organizations test code skills for amateur licenses.

Broadcasting tower database
An FCC database provides information about the height and year built of broadcasting towers in the US. It does not contain information about the structural types of towers or about the height of towers used by Federal agencies, such as most NDBs, LORAN-C transmission towers or VLF transmission facilities of the US Navy, or about most towers not used for transmission like the BREN Tower. These are instead tracked by the Federal Aviation Administration as obstructions to air navigation.

Criticism for use of proprietary standards
The FCC has been criticized for ignoring international open standards, and instead choosing proprietary closed standards, or allowing communications companies to do so and implement the anticompetitive practice of vendor lock-in.

In the case of digital TV, it chose the ATSC standard, even though DVB was already in use around the world, including DVB-S satellite TV in the U.S. Unlike competing standards, the ATSC system is encumbered by numerous patents, and therefore royalties that make TV sets and DTV converters much more expensive than in the rest of the world. Additionally, the claimed benefit of better reception in rural areas is more than negated in urban areas by multipath interference, which other systems are nearly immune to. It also cannot be received while in motion for this reason, while all other systems can, even without dedicated mobile TV signals or receivers.

For digital radio, the FCC chose proprietary HD Radio, which crowds the existing FM broadcast band and even AM broadcast band with in-band adjacent-channel sidebands, which create noise in other stations. This is in contrast to worldwide DAB, which uses unused TV channels in the VHF band III range. This too has patent fees, while DAB does not. While there has been some effort by iBiquity to lower them, the fees for HD Radio are still an enormous expense when converting each station, and this fee structure presents a potentially high cost barrier to entry for community radio and other non-commercial educational stations when entering the HD Radio market. (Under the subsidiary communications authority principle, FM stations could in theory use any in-band on-channel digital system of their choosing; a competing service, FMeXtra, briefly gained some traction in the early 21st century but has since been discontinued.)

Satellite radio (also called SDARS by the FCC) uses two proprietary standards instead of DAB-S, which requires users to change equipment when switching from one provider to the other, and prevents other competitors from offering new choices as stations can do on terrestrial radio. Had the FCC picked DAB-T for terrestrial radio, no separate satellite receiver would have been needed at all, and the only difference from DAB receivers in the rest of the world would be the need to tune S band instead of L band.

In mobile telephony, the FCC abandoned the "any lawful device" principle decided against AT&T landlines, and has instead allowed each mobile phone company to dictate what its customers can use.

Public consultation
As the public interest standard has always been important to the FCC when determining and shaping policy, so too has the relevance of public involvement in U.S. communication policy making. The FCC Record is the comprehensive compilation of decisions, reports, public notices, and other documents of the FCC, published since 1986.

1927 Radio Act
In the 1927 Radio Act, which was formulated by the predecessor of the FCC (the Federal Radio Commission), section 4(k) stipulated that the commission was authorized to hold hearings for the purpose of developing a greater understanding of the issues for which rules were being crafted. Section 4(k) stated that:

 * Except as otherwise provided in this Act, the commission, from time to time, as public convenience, interest, or necessity requires, shall... have the authority to hold hearings, summon witnesses, administer oaths, compel the production of books, documents, and papers and to make such investigations as may be necessary in the performance of its duties.

Thus, it is clear that public consultation, or at least consultation with outside bodies was regarded as central to the commission's job from early on. Though it should not be surprising, the act also stipulated that the commission should verbally communicate with those being assigned licenses. Section 11 of the act noted:

 * If upon examination of any application for a station license or for the renewal or modification of a station license the licensing authority shall determine that public interest, convenience, or necessity would be served by the granting thereof, it shall authorize the issuance, renewal, or modification thereof in accordance with said finding. In the event the licensing authority upon examination of any such application does not reach such decision with respect thereto, it shall notify the applicant thereof, shall fix and give notice of a time and place for hearing thereon, and shall afford such applicant an opportunity to be heard under such rules and regulations as it may prescribe.

Public hearings
As early as 1927, there is evidence that public hearings were indeed held; among them, hearings to assess the expansion of the radio broadcast band. At these early hearings, the goal of having a broad range of viewpoints presented was evident, as not only broadcasters, but also radio engineers and manufacturers were in attendance. Numerous groups representing the general public appeared at the hearings as well, including amateur radio operators and inventors as well as representatives of radio listeners' organizations.

"While some speakers at the 1927 hearings referred to having received 'invitations,' Herbert Hoover's assistant observed in a letter at the time that 'the Radio Commission has sent out a blanket invitation to all people in the country who desire either to appear in person or to submit their recommendations in writing. I do not understand that the commission has sent for any particular individuals, however' [Letter from George Akerson, assistant to Sec. Hoover, to Mrs. James T. Rourke, Box 497, Commerce Period Papers, Herbert Hoover Presidential Library (March 29, 1927)] (FN 14)"

Including members of the general public in the discussion was regarded (or at least articulated) as very important to the commission's deliberations. In fact, FCC commissioner Bellows noted at the time that "it is the radio listener we must consider above everyone else." Though there were numerous representatives of the general public at the hearing, some expressing their opinions to the commission verbally, overall there was not a great turnout of everyday listeners at the hearings.

Though not a constant fixture of the communications policy-making process, public hearings were occasionally organized as a part of various deliberation processes as the years progressed. For example, seven years after the enactment of the Radio Act, the Communications Act of 1934 was passed, creating the FCC. That year the federal government's National Recovery Agency (associated with the New Deal period) held public hearings as a part of its deliberations over the creation of new broadcasting codes.

A few years later, the FCC held hearings to address early cross-ownership issues; specifically, whether newspaper companies owning radio stations was in the public interest. These "newspaper divorcement hearings" were held between 1941 and 1944, though it appears that these hearings were geared mostly towards discussion by industry stakeholders. Around the same time, the commission held hearings as a part of its evaluation of the national television standard, and in 1958 held additional hearings on the television network broadcasting rules. Though public hearings were organized somewhat infrequently, there was an obvious public appeal. In his now famous "vast wasteland" speech in 1961, FCC chairman Newton Minow noted that the commission would hold a "well advertised public hearing" in each community to assure broadcasters were serving the public interest, clearly a move to reconnect the commission with the public interest (at least rhetorically).

On September 5, 2023, commissioner Nathan Simington held a public forum on the tech-focused social news site, Hacker News.

Media policy

 * 1978 Broadcast Policy Statement on minority ownership
 * Bleep censor
 * Broadcast Standards and Practices (US)
 * Censorship of broadcasting in the United States
 * Public Broadcasting Act of 1967
 * Public, educational, and government access (PEG)

Wireline/broadband policy

 * Comcast Corp. v. FCC
 * National broadband plans from around the world

Wireless policy

 * Frequency assignment authority
 * Open spectrum
 * Part 15 (FCC rules)

International

 * International Telecommunication Union
 * List of telecommunications regulatory bodies

title: Federal Communications Commission