Note: Your help in adding to this Glossary of hearing related terms will be most appreciated. We invite you to e-mail us any terms or words that you fell should be included. Thanks.
Acoustic feedback: Howl or whistle caused by the recirculation of acoustic output of an amplifying system. In a hearing aid the sound emanating from the receiver may reach (or feed back into) the microphone and be reamplified until it builds up into a high-pitched whistle.
acoustic nerve: The eighth cranial nerve, combining the nerves of hearing (cochlear) and balance (vestibular). syn: auditory nerve, vestibulocochlear nerve
aid, hearing: Electric amplifying device to make sounds audible to the individual with a hearing loss. Sound pressure waves are converted into electricity by a microphone. The electric impulses are then amplified through controlled electronic circuitry. The amplified electric impulses are then reconverted by a receiver (earphone) to pressure waves at a much more intense level to be presented to the impaired ear.
audiogram: Record of the threshold of sensitivity of hearing measured at several different (usually discrete) frequencies.
audiologist: Person trained in audiology - a specialist in the problems of hearing and deafness - in America and Canada excluding the field of medicine.
audiology: Study of hearing and hearing impairment. In Europe the term usually includes the study of the nature, causes, and treatment of diseases of the ear.
Behind-the-ear (BTE): hearing aids fit comfortably behind the ear and are attached to a custom earmold. Many can be modified with connections to external sound sources such as auditory training equipment, infrared listening systems or television.
binaural: (1.) Hearing with both ears. (2.) Of or pertaining to sound transmission from two separate sound sources, which may vary acoustically relative to the listener, as in the wearing of two hearing instruments.
Canal, auditory - external: The passage from the pinna to the eardrum through which sound waves travel. internal: An opening in the petrous portion of the temporal bone through which the auditory and facial nerves and blood vessels pass.
canal, spiral cochlear: Commonly known as the spiral canal of the cochlea. A portion of the bony labyrinth of the inner ear about 30 mm long making 2 3/4 turns about a central bony supporting structure known as the modiolus. Contains the scala tympani, scala vestibuli and cochlear duct. syn: Rosenthal's canal.
cerumen: Yellow or brown wax-like substance (earwax) secreted in the outer one-third of the external ear canal by the ceruminous glands. adj: ceruminal, ceruminous.
CIC: Completely-in the- Canal, a micro-miniature hearing aid that fits completely within the ear canal.
cochlea: winding tubular cavity within the inner ear, shaped like a snail-shell; contains the end-organ of hearing which finally changes the pressure waves of sound into nerve impulses. The central bony support of the cochlea is called the modiolus. A thin bony plate, the spiral lamina, extends from the modiolus and partially divides the cochlea. The division is completed by the fibrous support for the organ of Corti - the basilar membrane. One passageway above the divider begins at the oval window - the scala vestibuli. Another begins at the round window - the scala tympani. They are joined at the apex or helicotrema. Between the two is the scala media, or cochlear duct, which contains the organ of Corti. When extended the cochlear is about 1 1/3" (35 mm) long. It has 2 3/4 turns and is about 5 mm high and 9 mm in diameter. adj: cochlear.
cochlear implant: electronic device designed to stimulate the hearing mechanism. It utilizes a coil of wire embedded under the skin behind the ear with an extension of wire into the fluid of the inner ear (cochlea). It is activated by an amplifier, similar to a body-type hearing aid, carried in a pocket. There is sometimes a side benefit in that tinnitus is reduced.
Composite Noise: A sound stimulus generally composed of a large number of individual sinusoidal signals summed together for simultaneous presentation.. The result is a "noise-like" stimulus with controlled spectral characteristics. Commonly used to mimic the spectrum of spoken speech.
compression amplification: Method of limiting (or compressing) the amplification of loud sounds in comparison to weak sounds. When this type of circuit is used in a hearing aid or other amplifier, the wave form of a loud sound is less modified than when peak-clipping is used.
conductive hearing loss: one of three types of hearing loss (sensorineural and mixed hearing loss being the other two types). Produced by injury to, or problems with, the bones, eardrum and membranes which carry sound from the external ear through the middle ear to the inner ear.
Decibel: One-tenth of a bel. Commonly noted as dB. A decibel is a unit of measurement used to express logarithmic ratios (to the base of 10) of intensity, power, pressure, etc. Its reference base must always be given; e.g., re. input, re. .0002 dynes cm2 - or referred to in some manner as SPL (sound pressure level), SL (sensation level) etc. A decibel is approximately equal to a just noticeable difference (JND) in constant changes of intensity.
digitally programmable (computerized) hearing aids: offer todayıs most advanced technology. These aids are available in ITC (In-the-canal), ITE (In-the-ear), CIC (Completely in the Canal) and BTE (Behind-the-ear) models.
Ear (auris): Organ of hearing and balance that is divided into:
- The external ear includes the sound-collecting visible portion (auricle or pinna), the outer ear canal (external auditory meatus), and the outer surface of the eardrum (tympanum).
- The middle ear includes the inner surface of the eardrum, the ossicular chain (hammer, anvil, and stirrup - or malleus, incus, and stapes), the eustachian tube, and the outer surface of the oval and round windows (fenestrae).
- The inner ear includes the vestibule, the semi-circular canals, the inner surface of the oval and round windows, and the cochlea.
earache: Ear pain. Any ache or pain arising in the ear. Technically it may be called otalgia or otodynia.
eardrum: The eardrum (or tympanic membrane) stretches across the inner end of the external ear canal and forms the outer boundary of the middle ear. It reacts to sound waves and starts the ossicular chain moving.
ear specialist: Commonly accepted name for a medical ear specialist is otologist. He or she may also be known as an aural surgeon aurist. Other medical specialists especially interested in ears are variously known as otolaryngologists or otorhinolaryngologists - (oto) ear, (rhino) nose, (laryngo) throat specialists.
ear trumpet: a device with a large opening at one end designed to gather sound waves and direct them through a smaller opening into the outer ear canal.
ear wax: Wax in the external ear canal; syn: cerumen
echolalia: . involuntary repetition of words or phrases just spoken by someone else. Also known as echologia, echophasia, echophrasia, echo speech, and mimic speech.
eustachian tube: (Bartolomeo Estachio, Italian anatomist, 1510-1574). Tube about 1 1/2 inches (36 mm) long an 1/8" to 1/4" (3 mm to 6 mm) in diameter, leading from the nasopharynx to the middle ear. Normally makes possible equalization of pressure between the middle-ear and outside air. syn: auditory tube (tuba auditiva).
Frequency: Number of double vibrations or cycles per second (cps) of a sound wave train, typically referred to as hertz (Hz). For example, 256 Hz has the same pitch as middle C on the piano. Doubling this produces a tone one octave higher; if it is halved the tone will be one octave lower. Pitch is the psychological response to frequency.
Genetic deafness: Deafness transmitted by faulty genes. The trisomy syndromes exemplify the abnormal genetric transmissions that result in hearing impairments.
Hair cell : (1.) One of the specific sensory cells of the organ of hearing (organ of Corti). One end has hairlike projections (cilia) that are imbedded in or in contact with the tectorial membrane. The other end is in close contact with many nerve endings. There are about 400 hair cells per millimeter and about 80 cilia per cell. (2.) One of the specific sensory cells of the organ of balance within the vestibule and semicircular canals of the inner ear.
hearing: One of the five senses - the one that responds to sound pressure waves.
hearing aid.: An electronic amplifying device to make sounds audible to the individual with a hearing loss. Sound pressure waves are converted into electricity by a microphone. The electric impulses are then amplified through controlled electronic circuitry. The amplified electric impulses are then reconverted by a receiver to pressure waves at a much more intense level to be presented to the impaired ear. syn: hearing instrument.
hearing aid, ITE (In-the-ear): A hearing aid with all components encased in the earmold or in a case designed to fit entirely in the ear. In the Canal (ITC) and Completely in the Canal (ITC) hearing aid styles are also generically classified as ITE instruments.
hearing loss, conductive: Impairment of hearing due to the failure of sound pressure waves to reach the cochlea through the normal air conduction channels. This type of deafness is often responsive to medical or surgical treatment.
hearing, traveling wave theory of.: Movement of the footplate of the stapes causes a fluid wave to move along the basilar membrane with a rise and fall of amplitude. The point where the wave reaches its maximum amplitude is the point where the frequency of the sound is detected. Frequencies are highest toward the oval window and lowest toward the apex of the cochlea. Georg von Bekesy received the Nobel prize in 1961for his discovery of the traveling wave phenomenon that resulted in this theory.
Helmholtz' resonance theory.: (From Hermann von Helmholtz, German physician and physicist, 1821-1894). The theory that the hair cells within the organ of Corti act as resonators - each with its own natural period of vibration and each responding only to one tone of one particular frequency.
hertz, Hz (hertz). The term used for cycles per second - named in honor of the German physicist, Heinrich Hertz, 1857-1894.
high fidelity: The reproduction or amplification of sound waves with a minimum of distortion.
high frequency: An inexact term which, in audiology, generally refers to any frequency above 1000 Hz.
hysterical deafness: Nonorganic or functional hearing loss sometimes unconsciously developed as a psychic protection under conditions of severe emotional strain. syn: conversion deafness.
Impression : A cast made of the contours within the external ear from which an earmold (for BTE instruments) or custom shell (for ITE, ITC and CIC instruments) is made. Impressions typically are made using a silicone or audalin material which is plastic for insertion and cures within a few minutes for removal.
In-the-canal (ITC) and in-the-ear (ITE) aids are custom-designed to fit the wearer's ear. Inconspicuous once in place, they fit comfortably and securely inside the ear or ear canal, to most closely imitate the natural hearing process. These one-piece models have no cords or wires. Nearly 80 percent of all aids recommended today in North America are either ITC, CIC or ITE models.
inner ear: Portion of the ear bounded externally by the oval and round windows and internally by the internal auditory canal. It contains the cochlea and semicircular canals.
jumper : One who jumps at a loud sound as the result of a nervous disorder.
just noticeable difference (jnd) Also known as difference limen (DL) or differential threshold. The smallest change in frequency or intensity that can be recognized. As the smallest recognizable change in intensity, it approximates the decibel.
Keratosis obturans: A hard plug of wax and dry skin sometimes found in the external and auditory canal.
kinesthetic cues Bodily sensations that aid a deaf person in controlling speech, e.g., jaw and lip positions and nasal vibrations.
kymograph: A device that makes a record of sound vibrations by means of a stylus activated by a tuning fork as a rotating cylinder passes beneath.
Lip read : To understand by close observation of the speaker's lips. It is now more commonly known as speechreading, since facial expression and gestures enter into communication. n: lipreading
loudness: Subjective sensation of the effect of amplitude or intensity. It is determined partly by the number of auditory nerve fibers activated by the sound wave and partly by the number of impulses carried by each fiber.The unit of measurement of subjective loudness is the "sone."
loudness level: LL. the loudness level of a sound is determined by comparison for equal loudness with a 1000 Hz tone re .0002 dyne c/m2 when heard binaurally in sound field. The unit of loudness level is known as the "phon." It is numerically equal to the SPL of the 1000 Hz tone, but varies with frequency.
low frequency: An inexact term that is generally refers to a frequency of 1000 Hz and below.
Malleus plural - mallei: Also called the hammer, the malleus is the first and largest of the ossicles. The handle is attached to the eardrum, while the head is attached to the roof of the tympanic cavity by the superior malleolar ligament, and moves (articulates) with the incus (anvil). It is about 8 mm long.
masking noise.: (1). A mixture of frequencies made up in various ranges - narrow, broad, white, or complex - introduced into one ear to prevent the hearing by that ear of a tone or sound presented to the other ear. (2). any unwanted sound that interferes with the ability to hear the wanted sound.
mastoid: Raised portion of the temporal bone behind the external ear: the mastoid process.
mastoiditis: Inflammation within the air cells of the mastoid
membrane, drum: The eardrum. Also called tympanic membrane or the drumskin.
Menier's disease, Meniere's syndrome: (Prosper Meniere, French physician, 1799-1862). Endolymphatic hydrops - the malfunction of hearing and balance caused by excessive inner ear fluids. A condition whose intermittent symptoms include dizziness, nausea, tinnitus, and progressive deafness. syn: labyrinthine hydrops.
microphone, sound-probe: Tiny microphone on a thin rod or cylinder designed to study sound waves in small confined spaces such as the ear canal with a minimum of disturbance to the wave form. Also known as a probe-mic system.
middle ear: Auris media, or tympanic cavity. The portion of the hearing mechanism between the outer and inner ears. Consists of the eardrum, the ossicles, the opening of the eustachian tube, the oval window, and the round window.
mixed hearing loss: One which contains elements of both conductive and sensorineural hearing loss.
modulation, frequency: Variation of the frequency of a radio carrier wave in accordance with an audio or other signal.
Narrow-band Noise: A sound stimulus generally produced by one-third octave band filtering of broad-band white noise.
nerve, cochlear Branch of the eighth cranial (acoustic) nerve that arises in the cochlea and conveys sound stimuli to the brain. The nerve of hearing.
Organ of Corti : A structure resting on the basilar membrane within the cochlear duct (scala media). It contains the essential sensory elements of hearing, the hair cells, and their supporting cells. The function of the hair cells is to convert sound pressure waves into nerve impulses, which are transmitted by way of the eighth cranial nerve to the brain. It is the end-organ of hearing. syn: organum spirale.
ossicles, auditory: The small bones of the middle ear that convey sound impulses from the eardrum to the oval window. They are known as the hammer (malleus), anvil (incus), and stirrup (stapes).
otitis: A broad term for inflammation of the ear.
otogolist: Medical doctor specializing in problems of the ear. syn: aurist - seldom used.
otosis: pl. otoses: (1). Mishearing or misunderstanding of spoken sounds.
(2). mispronunciation of words resulting from faulty hearing.
Perforated eardrum: An eardrum that has been ruptured by accident or disease. The reduction in hearing sensitivity usually amounts to about 5 or 10 dB.
phoneme: (1). One of the smallest units of speech (or class of phones) that distinguishes one word from another: e.g., p, b, and f in pan, ban, and fan. (2). Hearing of imaginary voices.
pinna: The portion of the ear that is visible on the side of the head. adj. pinnal; syn: auricle
pitch, absolute: The ability to identify unerringly the fundamental frequency of a tone that is heard.
Probe microphone: A miniature microphone typically connected to a soft silicone tube (probe tube) and inserted into the ear canal to perform real-ear measurements. Commonly used to measure the natural resonance of the unoccluded ear canal (for hearing aid selection) and the aided ear canal (for hearing aid adjustment).
profound deafness: Extreme hearing impairment bordering on total deafness. A degree of loss so severe that hearing aid amplification must be supplemented by speechreading at all times to be effective. Numerically, it is generally considered to be an average of over 90 dB at 500, 1000, and 2000 Hz audiometrically (ANSI). Pure tone A continuous sinusoid of a single frequency. Commonly used in basic hearing screening tests.
Quinine : a drug formerly used for the prevention of malaria. Now a part of many cold remedies and abortifacients, it may cause deafness in susceptible individuals.
Range of comfortable loudness : RCL. A range of sound pressure intensities that are subjectively comfortably loud for the individual.
Real Ear Aided Response (REAR): The sound pressure level, as a function of frequency, at a specified point in the ear canal for a specified soundfield, with a hearing aid in place and turned on. Primarily a measurement of the hearing aid's response, and used as a reference for insertion gain calculations. (REAR-REUR=REIG)
real-ear attenuation: A measurement of the amount by which ear protectors lessen sound pressure reaching the eardrum of a paricular observer. It is expressed in decibels of difference between thresholds of audibility when the ears are open and when they are protected.
Real Ear Insertion Response (REIR): The difference, in decibels as a function of frequency, between the REUR and the REAR measurements taken at the same measurement point in the same soundfield. The Real Ear Insertion Gain (REIG) is the value, in decibels, of the REIR at a specific frequency. REIR is the amount of gain delivered to a patient wearing a hearing aid that they did not have before the hearing aid fitting.
real-ear gain: The additional sound pressure reaching the eardrum when a hearing aid is used - compared to the sound pressure reaching the eardrum without a hearing aid. syn: etymotic, orthotelephonic, or insertion gain (REIG).
Real Ear Occluded Response (REOR): The sound pressure level, as a function of frequency, at a specified point in the ear canal for a specified soundfield, with a hearing aid in place and turned off. Primarily a measurement of the effect of the placement of the hearing aid or earmold in the ear.
Real Ear Unaided Response (REUR): The sound pressure level, as a function of frequency, at a specified point in the unoccluded ear canal for a specified soundfield. Primarily a measurement of the resonance characteristics of the ear canal and the concha.
receiver: A device that converts (transduces) electrical impulses into sound waves (or signals). syn: earphone, speaker, transducer.
reflex, acoustic: The reflex contraction of the intra-aural muscles (tensor tympani and stapedius) in reponse to sound. syn: intraaural reflex; cochlear reflex; auditory reflex.
Sensorineural hearing loss: Hearing loss (also known as nerve deafness), one in which the bones, eardrum and membranes are intact, but a deterioration of the inner ear is present. This may be caused by the natural aging process, or degeneration of the nerves leading from the inner ear to the brain.
severe deafness: A hearing loss between 70 dB and 90 dB when the hearing threshold level at 500, 1000 and 2000 Hz in the better ear is averaged.
sign language: A system of conventional symbols or gestures made with the hands to help the deaf communicate. It is distinct from finger spelling. There are various systems, among them American Sign Language, ASL (AMESLAN); Linguistics of Visual English, LOVE or LVE; Seeing Essential English, SEE1; Signed English, SE (Siglish); Signing Exact English, SEE2; Systematic Sign Language, SLL.
Signed English (Siglish): a modification of American Sign Language (AMESLAN) developed by Harry Bornstein and associates at Gallaudet College. It is designed to present a formalized gesture system that will help children learn to communicate more easily with better syntax and grammar.
short increment sensitivy index (SISI): A test of the ability to recognize one decibel increases in intensity during a series of bursts of pure tone presented 20 dB above threshold.
sound: (1). The sensation resulting from stimulation of the auditory mechanism by air waves or vibrations. (2). An instrument that may be inserted into a cavity or tube (e.g., eustachian) for diagnosis or treatment.
stapes: Also known as the stirrup, the stapes is the third and inner bone of the ossicular chain. Moved by the incus, the stapes vibrates in the oval window.
TILL: Treble Increase at Low Levels. A type of compression amplification system which attentuates (reduces) the amount of high frequency gain as input signal levels increase.
Tinnitus: Noises seeming to originate within the ear itself; syn: susurrus aurium, tinnitus cerebri, tinnitus aurium.
tone deafness: Inability to recognize musical tones or pitch differences. In extreme cases it is known as amusia.
treble: The highest voice part in harmonic music. In upper half of the whole vocal or tonal range.
tympanic membrane: The eardrum. Also called drum membrane and drumhead. It stretches across the inner end of the external ear canal and forms the outer boundary of the middle ear. It reacts to sound waves and starts the ossicular chain moving. It is about 1/3 inch (7 or 8 mm) in diameter.
Ultrasonic sound: Sound pressure waves whose frequency is above the audible range. Sometimes called ultra-audible sound.
uncomfortable loudness or uncomfortable loudness level.: UCL or ULL. The intensity level at which a tone or sound subjectively becomes uncomfortably loud.
utricle, utriculus: . The larger of the two sacs that occupy a portion of the membranous labyrinth of the vestibule of the inner ear. (The smaller sac is the saccule).
utriculitis: (1.) inflammation involving the utricle of the vestibule. (2.) inflammation of the inner ear.
Vertigo: Dizziness or a sensation of whirling or irrigular motion that arises from problems within the vestibular portion of the inner ear. Objective vertigo is the name given the sensation that the world is spinning about the patient. Subjective vertigo indicates the patient feels he is moving in space. adjective: vertiginous.
vestibule: Portion of inner ear between cochlear and semicircular canals. It contains the saccule and the utricel.
volume: Used interchangeably for either intensity or loudness.
Warble tone: A tone resulting from rapid modulations of frequency within fixed limits around the basic pure tone frequency. Commonly used in real ear measurements as they are not easily influenced by standing waves from reflective surfaces.
wave, sound: A change in the arrangement of molecules in a medium into successive patterns of compression and rarefaction.
whisper test: An obsolete and inadequate method of testing hearing.
Xanthomatosis: a metabolic disorder marked by deposits of yellow or orange nodules in the skin. It is sometimes associated with tinnitus.
Y-cord: a hearing aid cord that divides the electrical impulse from one transmitter to two receivers. A modified form is known as a V-cord. syn: pseudobinaural.
Zone of normal hearing: The range of thresholds for speech from 0 to 25 dB (ISO).
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