Glossary

A:

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 (loudspeaker) 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, vestibulocochlearnerve.

aid, hearing An electric amplifying device designed 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 (loudspeaker) to pressure waves at a much more intense level to be presented to the impaired ear. syn: hearing instrument.

audiogram A record of the threshold of sensitivity of hearing measured at several different (usually discrete) frequencies.

audiologist A person trained in audiology; a specialist in the problems of hearing and deafness -- in America and Canada excluding the field of medicine.

audiology The 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.

B:

Behind-the-Ear (BTE) A type of hearing aid designed to fit behind the ear, which transmits sound to the ear canal via tubing and 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.

C:

canal, external auditory The passage from the pinna to the eardrum through which sound waves travel.

canal, internal auditory 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 A 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.

cochlea The winding tubular cavity within the inner ear, shaped like a snail-shell; contains the organ of Corti, 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 basilar membrane, which is the fibrous support for the organ of Corti. One passageway above the divider begins at the oval window, or scala vestibuli. Another begins at the round window, or 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 cochlea 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. See also: ORGAN OF CORTI.

cochlear implant An 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.

Completely-in the-Canal (CIC) A type of hearing aid that is micro-miniature in size and fits entirely within the ear canal to most closely imitate the natural hearing process. It is custom-designed to fit the contours of the wearer's ear canal.

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 A method of limiting ("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 that carry sound from the external ear through the middle ear to the inner ear.

D:

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; for example, "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.

digital (computerized) hearing aids Hearing aids that incorporate digital signal processing, the latest in hearing aid technogy. Digital signal processing is the technology that gives audio Compact Discs (CDs) their clear sound. Digital aids are available in CIC (Completely-in-the-Canal), ITC (In-the-Canal), ITE (In-the-Ear), and BTE (Behind-the-Ear) models.

E:

e2e wireless™ Siemens proprietary wireless technology that enables the left and right hearing instruments to function as one binaural hearing system. Both instruments exchange vital information about the listening environment, then make instantaneous decisions regarding digital signal processing and wearer controls. The result is better hearing, from both ears, whatever the listening environment.

ear The organ of hearing and balance. syn: auris. Divided as follows:
The external ear comprises 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 comprises the inner surface of the eardrum, the ossicular chain (malleus [hammer], incus [anvil], and stapes [stirrup]), the eustachian tube, and the outer surface of the oval and round windows (fenestrae).
The inner ear comprises the vestibule, the semi-circular canals, the inner surface of the oval and round windows, and the cochlea.

earache Any ache or pain arising in the ear. Technically it may be referred to as otalgia or otodynia.

eardrum A membrane that 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. syn: tympanic membrane, drum membrane, drumhead.

ear specialist Commonly referred to as an otologist; also aural surgeon aurist. Other medical specialists especially interested in ears are variously known as otolaryngologists or otorhinolaryngologists (oto: ear, rhino: nose, laryngo: throat).

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 The involuntary repetition of words or phrases just spoken by someone else. Also known as echologia, echophasia, echophrasia, echo speech, and mimic speech.

Eustachian tube [After Bartolomeo Eustachio, Italian anatomist, 1510-1574]. A 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. Enables equalization of pressure between the middle ear and outside air. syn: auditory tube, tuba auditiva.

F:

frequency The 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; halving it produces a tone one octave lower. The psychological response to frequency is referred to as pitch.

G:

genetic deafness Deafness transmitted by faulty genes. The trisomy syndromes exemplify the abnormal genetic transmissions that result in hearing impairments.

H:

hair cell 1. One of the specific sensory cells of the organ of hearing (organ of Corti). One end has hair-like projections (cilia) that are imbedded in, or are 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 electric amplifying device designed 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 (loudspeaker) to pressure waves at a much more intense level to be presented to the impaired ear. syn: hearing instrument.

hearing instrument see HEARING AID.

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 The theory that the 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 1961 for his discovery of the traveling wave phenomenon, which resulted in this theory.

Helmholtz' resonance theory [After 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) The term used for cycles per second. [After Heinrich Hertz, German physicist, 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.

I:

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 of soft consistency for insertion and cures within a few minutes for removal.

In-the-Canal (ITC) A type of hearing aid that fits almost entirely in the ear canal, making it inconspicuous once in place. It is custom-designed to fit the contours of the wearer's ear.

In-the-Ear (ITE) A type of hearing aid with all components encased in a shell custom-designed to fit entirely in the wearer's ear, with no external cords or wires. In-the-Canal (ITC) and Completely-in-the-Canal (ITC) hearing aid styles are also generically classified as ITE instruments. Nearly 80 percent of all aids recommended today in North America are either ITE, ITC or CIC models.

inner ear The 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.

J:

just noticeable difference (JND) The smallest change in frequency or intensity that can be recognized. As the smallest recognizable change in intensity, it approximates the decibel. syn: difference limen (DL), differential threshold.

K:

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, such as 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 it.

L:

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 The 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.

M:

malleus Also called the hammer, the malleus is the first and largest of the ossicles, or bones of the middle ear. 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. pl. mallei

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 The raised portion of the temporal bone behind the external ear. syn: mastoid process

mastoiditis Inflammation within the air cells of the mastoid.

membrane, drum The eardrum. syn: tympanic membrane, drumskin

Meniere's disease, Meniere's syndrome [After Prosper Meniere, French physician, 1799-1862]. 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: endolymphatic hydrops, 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. A component of a probe-mic system.

middle ear The portion of the hearing mechanism between the outer ear and inner ear. Consists of the eardrum, the ossicles, the opening of the eustachian tube, the oval window, and the round window. syn: auris media, tympanic cavity

mixed hearing loss A hearing impairment that 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 signal or other signal.

N:

narrow-band noise A sound stimulus generally produced by one-third octave band filtering of broad-band white noise.

nerve, cochlear The branch of the eighth cranial (acoustic) nerve that arises in the cochlea and conveys sound stimuli to the brain. The nerve of hearing.

nerve deafness see SENSORINEURAL HEARING LOSS.

O:

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.

otologist A 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.

P:

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.

phon The unit of loudness level, numerically equal to the SPL of the 1000 Hz tone, but varies with frequency.

phoneme 1. One of the smallest units of speech (or class of phones) that distinguishes one word from another; for example: p, b, and f in pan, ban, and fan. 2. The hearing of imaginary voices.

pinna The portion of the ear that is visible on the side of the head. adj: pinnal; syn: auricle

pitch The psychological response to frequency.

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.

probe-microphone measurements Measurements used to determine the real-ear gain and output of hearing aids. Probe-microphone measurements are helpful in fitting hearing aids to desired targets, adjusting hearing aids based on patient feedback, and verifying special hearing aid features.

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).

programmable (computerized) hearing aids Hearing aids that incorporate advanced programmable analog technology. Programmable aids are available in CIC (Completely-in-the-Canal), ITC (In-the-Canal), ITE (In-the-Ear), and BTE (Behind-the-Ear) models.

pure tone A continuous sinusoid of a single frequency. Commonly used in basic hearing screening tests.

Q:

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.

R:

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 sound field, 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 (see REAL-EAR INSERTION GAIN).

real ear attenuation A measurement of the amount by which ear protectors lessen sound pressure reaching the eardrum of a particular 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 sound field. 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 measurements Usually refers to the measurement of gain or output of a hearing aid, turned on, placed in the patient's ear. Real-ear measurements can be conducted using probe-microphone measurements, soundfield testing, or functional gain.

Real-Ear Aided Gain (REAG) The difference in decibels, as a function of frequency, between the sound pressure level (SPL) at a specified measurement point in the ear canal and the sound pressure level at the field reference point, for a specified sound field, with the hearing aid (and its acoustic coupling) in place and turned on.

Real-Ear Aided Response (REAR) The sound pressure level (SPL), as a function of frequency, at a specified point in the ear canal for a specified sound field, with a hearing aid in place and turned on.

Real-Ear Insertion Gain (REIG) The difference in decibels, as a function of frequency, between the Real-Ear Aided Gain (REAG) and the Real-Ear Unaided Gain (REUG), taken with the same measurement point and the same sound field conditions.

Real-Ear Occluded Gain (REOG) The difference in decibels, as a function of frequency, between the sound pressure level (SPL) at a specified measurement point in the ear canal and the sound pressure level at the field reference point, for a specified sound field, with the hearing aid (and its acoustic coupling) in place and turned off.

Real-Ear Occluded Response (REOR) The sound pressure level (SPL), as a function of frequency, at a specified point in the ear canal for a specified sound field, 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 Gain (REUG) The difference in decibels, as a function of frequency, between the sound pressure level (SPL) at a specified measurement point in the ear canal and the sound pressure level at the field reference point, for a specified sound field, with the ear canal unoccluded (unblocked).

Real Ear Unaided Response (REUR) The sound pressure level (SPL), as a function of frequency, at a specified point in the unoccluded ear canal for a specified sound field. 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 response to sound. syn: intraaural reflex, cochlear reflex, auditory reflex.

S:

saccule The smaller of the two sacs that occupy a portion of the membranous labyrinth of the vestibule of the inner ear. (The larger sac is the utricle).

sensorineural hearing loss A hearing impairment 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. syn: nerve deafness.

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, LVE), Seeing Essential English (SEE1), Signed English (SE, Siglish), Signing Exact English (SEE2), and Systematic Sign Language (SLL).

Signed English (SE, 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 sensitivity 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 (for example, the eustachian tube) for diagnosis or treatment.
sound wave A change in the arrangement of molecules in a medium into successive patterns of compression and rarefaction.

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. pl. stapes, stapedes

T:

TILL Treble Increase at Low Levels. A type of compression amplification system that attenuates (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.

traveling wave theory of hearing The theory that the 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 1961 for his discovery of the traveling wave phenomenon that resulted in this theory.

treble The highest voice part in harmonic music; the upper half of the whole vocal or tonal range.

tympanic membrane A membrane that 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. syn: eardrum, drum membrane, drumhead

U:

ultrasonic sound Sound pressure waves whose frequency is above the audible range. syn: 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 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). syn: utriculus

utriculitis 1. inflammation involving the utricle of the vestibule.
2. inflammation of the inner ear.

V:

vertigo Dizziness or a sensation of whirling or irregular 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. The term objective vertigo indicates the patient feels he is moving in space. adj: vertiginous

vestibule The portion of the inner ear between the cochlea and semicircular canals. It contains the saccule and the utricle.

volume A term used interchangeably to refer to either intensity or loudness.

W:

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.

X:

xanthomatosis A metabolic disorder marked by deposits of yellow or orange nodules in the skin. It is sometimes associated with tinnitus.

Y:

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.

Z:

zone of normal hearing The range of thresholds for speech from 0 to 25 dB (ISO).

Portions of this glossary of terms were used with permission from the 1983 edition of the "Comprehensive Dictionary of Audiology" by James H. Delk. Published by Williams & Wilkins, 351 Camden Street, Baltimore, Maryland, 21201. (800) 632-6423.
Portions of this glossary of terms were derived from "Probe Microphone Measurements, Hearing Aid Selection and Assessment" by H. Gustav Mueller, Ph.D., David B. Hawkins, Ph.D., and Jerry L. Northern, Ph.D. Published by Singular Publishing Group, Inc., 4284 41st Street, San Diego, CA 92105-1197.