Hearing Loss Dictionary

Reading about hearing loss can get confusing sometimes. There are plenty of technical terms you may have never seen before. <br /><br />At SayWhat, we created our own "Hearing Loss Dictionary" to help you better read and understand the information you come across.
Reading about hearing loss can get confusing sometimes. There are plenty of technical terms you may have never seen before.

At SayWhat, we created our own "Hearing Loss Dictionary" to help you better read and understand the information you come across.

It refers to the clarity or audibility of sound

Adaptive directional microphones:
Directional microphone system that can adapt based on the location of the noise.

Adaptive feedback cancellation:
It refers to the digital process in which a filter is used within the amplifier of a digital hearing aid to cancel feedback the moment it's detected, without reducing or altering the hearing aid’s response. The filter will automatically adapt if the feedback is caused by a different or changing sound environment.

An electronic sound processor located inside of a hearing aid that increases the incoming signal to improve the audibility of the outgoing signal.


The absence of sound; deafness

Analog hearing aid: 
Analog hearing aids use older and simpler technology, when compared to digital hearing aids. Not everyone can adjust to a digital hearing aid after a lifetime of wearing analog hearing aids. 

ASP (Bill Circuitry):
Stands for automatic signal processing bass increase at low levels. This circuit also decreases the bass at high levels. This circuit is intended for wearers who frequent noisy environments where low-frequency noises is a constant factor. Harsh or shrill sounds are not amplified but reduced by this circuit.

ASP (Pill Circuitry):
Stands for the automatic signal processing programmable increase at lower levels. Is a more versatile version of the BILL and TILL circuits, because it can be programmed to automatically perform as a BILL circuit in one channel and a TILL circuit on another. The user can switch as listening environments change.

ASP (TILL Circuit):
Stands for automatic signal processing treble increase at low levels. This circuit also decreases the high-frequency volume at high levels. This circuit is used for wearers that require volume increase for quiet sounds. Harsh or shrill sounds are not amplified but pass through the circuit unaltered.


A graph on which to record the auditory threshold by the frequency of a patient’s hearing.

A hearing healthcare professional who has a Masters Degree (M.S. or M.A.) or Doctorate Degree (Au.D. or Ph.D.) in audiology or a related field of study. Some activities that audiologists are involved with are the assessment and treatment of hearing and vestibular disorders, the dispensing of hearing aids, research, industrial consultation, and/or teaching.

The science that studies hearing

The electronic piece of equipment employed by a hearing healthcare professional to assess the hearing thresholds and speech awareness/processing ability of an individual.

The measurement of hearing

Having to do with the ear or hearing

Auditory nerve:
Connects the inner nerve and the brain; serves in hearing and balance.

Aural rehabilitation:
Therapy or training sessions designed to improve communication skills.

The cartilaginous, visible portion of the external ear and the point of difference between the human ear and that of other mammals. Also known as the pinna.

Automatic Signal Processing (ASP):
The family of hearing aid circuits which automatically change the volume and frequency response (such as bass, midrange, and treble) as a function of the sounds entering the hearing aid’s microphone.

Hearing aid batteries power the hearing aid device. Batteries need to be replaced every few weeks to every few days, depending on your usage. The four popular sizes of disposable hearing aid batteries available on the market are 10 (yellow), 312 (brown), 13 (orange), and 675 (blue). These zinc-air button disposable batteries are smaller than the diameter of a dime. Rechargeable hearing aid batteries are available as well. 

Stands for “Bilateral Contralateral Routing of Signal”. Is a feature in dual hearing aid set-ups. BICROS systems are sometimes recommended when both ears have hearing loss, but one ear hears substantially “better” than the other.


A term used to signify that both ears or both sides of the head are involved (Example: the patient has bilateral hearing loss.)

Refers to when sound is presented to both ears (i.e., She wears binaural amplification).

Binaural advantages
The benefits derived from the average patient, with equal or fairly equal hearing loss, from the use of hearing aids on both sides.

Bluetooth™ wireless technology
A type of signal technology that allows digital instruments to communicate wirelessly. It uses short-wavelength UHF radio waves in the ISM band from 2.4 to 2.485 GHz

Body hearing aid
A hearing aid with a microphone, amplifier, and battery worn on the chest connected to an ear-worn receiver with a cord.

Bone-conduction thresholds
The lowest level that an individual can hear a pure-tone stimulus. It is measured through a headpiece placed on the forehead that monitors the vibrations of the mastoid bone. Bone-conduction threshold testing attempts to assess the ability of the sensory and neural auditory systems without the sound passing through the outer and middle ear.

BTE (Behind-the-ear) hearing aid:
The group of hearing aids that are worn behind the ear. Does not refer to where the speaker is located, but where the circuitry and case of the device sits on the ear.


The scientific term for earwax.

A benign expanding mass which can form in the middle ear cavity. It is made up of skin and cholesterol crystals. The mass can become infected and cause other problems in the middle ear.

CIC (Completely-in-Canal)
Type of hearing aid that fits beyond the visual opening of the ear canal.

Circuit Noise:

Extraneous sounds present in the output of a hearing aid that is related to the function of the hearing aid’s mechanism, not due to external sounds.

Class A Circuits:
A type of circuit that produces a linear amplification to all frequencies with equal intensities. This types of circuits are found in basic lower price amplification devices.

Part of the inner ear that has the shape like a snail. Vibrations in the fluid-filled cochlea cause tiny hair cells to vibrate and generate nerve impulses that then travel to the brain with sound signals.

Cochlear Implant:

An electronic device, a portion of which is surgically implanted into the inner ear, that is designed to provide a sensation of sound to deaf individuals.

Communication Disorder:
Any abnormality in speech, language, or hearing processes that results in an inefficient exchange of information.

Compression Amplification:
The action of decreasing (Compressing) volume as the loudness of sound increases at the hearing aids user’s ear. Managing to create a more natural and clear volume increase.

Compression Threshold (Kneepoint):

It is the predetermined level of dB’s where the compression circuit starts to reduce the gain (volume). Some circuits allow this threshold to be digitally programmed and customized to the wearer's needs.

Conductive Hearing Loss:

A decrease in an individual’s ability to hear a particular sound due to an inefficiency or disruption in the outer ear or middle ear system. A conductive hearing loss is when the sounds are somehow “blocked” as they travel from the pinna to the cochlea.

Cone Of Light:

A triangular brightness visible on the lower portion of the tympanic membrane (eardrum) during otoscopy due to a reflection of the light coming out of the otoscope.

Congenital Hearing Loss:
The presence of hearing loss at or before birth.

CROS (Contralateral Routing of Signal):
a feature used on dual hearing aid setups when one hearing aid passes signals to the other hearing aid. This feature is recommended for users with single-sided deafness (SSD) or for users with very poor word and frequency recognition in one ear.


abbreviation for Decibel. A Decibel is a unit of measurement for sound intensity or loudness. One decibel is 1/10 of a bel - named after Alexander Graham Bell.

Degenerative hearing loss:
A hearing impairment that worsens over time.

Degree of hearing loss:

Terms utilized to represent the thresholds of hearing graphed onto an audiogram to help describe the different degrees of hearing impairment expected. One commonly used scale is: mild = 25 to 40 dB, moderate = 41 to 55 dB, moderately-severe = 56 to 70 dB, severe = 71 to 90 dB, and profound = greater than 90 dB.


A more current type of hearing aid that digitizes a sound, utilizing an analog-to-digital converter, prior to processing the sound. The sound represented in a digitized format can be manipulated and processed more efficiently.


Perceiving a single tone as multiple tones or multiple harmonics.

Digital hearing aid:
An instrument that converts the electric signal from the microphone to digital values for processing, then converts them back to electric (sound) signals for the ear.

Direct audio input:

The feature that allows using a jack to plug in an external device to receive sound directly from it. This can be a phone a TV or any other entertainment system.

Directional microphone:
A microphone that is more sensitive to sound approaching from one direction.

Dri-aid kit:
Various products containing drying agents or utilizing heat that is used to lessen the amount of harmful moisture built-up in a hearing aid.

Short for digital signal processing.

Dynamic range:

The difference in dB between the threshold of hearing and discomfort level.

Ear canal:

The external auditory meatus. The hole in the temporal bone that tunnels the sound from the pinna to the eardrum (tympanic membrane).


The tympanic membrane. A thin layer of skin that separates the ear canal from the middle ear cavity. The eardrum converts sound waves into vibrations.


A portion of a Behind-The-Ear hearing aid that is designed to bend over the top of the ear and connect the aid’s casing to the tubing.

An impression of an ear canal used to mold the shell of a hearing aid. It is made using silicone or other impression materials.


When two hearing aids communicate with each other. For volume, programming or microphone direction purposes. This eliminates the need of having to set each hearing aid individually.

Eng (Electronystagmography):
A special series of tests utilized to evaluate the vestibular system during which eye movements are measured electro-physically.


An undesired effect of some anti-feedback circuitry in which the feedback reduction algorithm attempts to eliminate an incoming sound as if the sound is feedback when it truly is not.

A body’s ability to maintain physical balance by using vestibular, visual and proprioceptive (sense of touch) input.

The source or cause of a hearing loss.

Eustachian tube:
A small connection between the throat and the middle ear cavity which in the normal human ear system is utilized to equalize the pressure in the middle ear cavity to the pressure in the atmosphere surrounding the body.

Eustachian tube dysfunction:

When the tube that connects the throat and the middle ear cavity becomes inflamed or blocked. Eustachian tube dysfunction can lead to negative pressure, fluid in the middle ear, and/or middle ear infections.

Expansion technology:

A digital process which allows the hearing aid to generate lower gain (volume) for softer sounds. This improves the overall quality of the sound from the hearing aid when worn in quiet situations by reducing low-level noise.

Extended-wear hearing aids:

Hearing aids that can be used for long periods of time before the battery or other components need to be changed, times range from a few weeks to a month.

External receiver:
Refers to the hearing aids that have the speaker outside the case and placed inside the canal and the processor (other components of the hardware) inside the case sitting behind the ear. An RIC (Receiver in Canal) device is an example of these type of design.


A bone growth in the ear canal.

The distortion generated when the sound that has been amplified is picked up by the microphone and amplified again on a loop.


A device that allows for some frequencies to pass through while attenuating others.

FM integration:

When the hearing aid has an FM receiver that picks up signals from an FM transmitter. This type of signal transmission is used when connecting to lectures, concerts or other FM signal transmissions to isolate the speaker or certain sounds from the ambient noise.


An abnormal hole or rupture in the window that connects the middle ear cavity and the cochlea, allowing the leakage of inner ear fluid (perilymph) into the middle ear and often resulting in hearing loss and dizziness.

Flat audiogram:

A description of the graph of an individual’s hearing thresholds in which the degree of loss present is similar or equal for low, mid and high frequencies.


The number of complete oscillations per unit of time, measured in number of cycles per second and expressed in Hertz (Hz).


The amount of dB that a sound can be increased.

Gain control:
A device that allows the gain (volume) to be adjusted (see volume control).

Gain reduction:
Used in multichannel hearing aids to automatically lower the gain in a specific channel to control feedback.

Hair Cells:
Cells present in the cochlea that convert the mechanical energy present in sound vibrations into electrical activity. Hair cells have cilia on one side which are stimulated by movement and on the other side are connected to fibers of the VIIIth cranial nerve, which carries the impulse to the brain.

Hard of Hearing:
A term used to describe hearing-impaired individuals with mild to severe/profound hearing impairment who are not deaf.

Head shadow effect:

The knowledge that a sound source presented on one side of the head is less intense when measured on the other side of the head, due to the sound having to make its way around the head.

Hearing aid:

A wearable device that aids or corrects human hearing.

Hearing aid amplifier: 
(see Personal Sound Amplifier)

Hearing aid specialist:
A non-audiologist. A hearing healthcare professional who holds a state license that allows him or her to dispense hearing aids.

Hearing loss:
The inability to perceive the presence of a sound at normal hearing levels.


Shell style with a free field design allowing for a maximum venting of the ear canal.

Hereditary hearing loss:

A hearing loss or a propensity for hearing loss that is transferred via genes from parent to offspring.

Hertz (Hz):
Cycles per second. A name given to describe the frequency or pitch of a sound.

High-frequency hearing loss:

A hearing impairment which is only present or is significantly more prevalent in the higher pitches.

High pass filter:
A filter that allows high frequencies to pass through and attenuates low frequencies.Impression: A mold of the concha and ear canal made by a hearing healthcare professional to assist the hearing aid manufacturer in producing a custom fit hearing aid that sits in and seals the user’s ear appropriately.

IIC (Invisible-in-the-canal):
A small hearing aid designed to fit deep in the ear canal, completely out of sight, in some cases only an external small grab cable sits in the canal entrance.


The middle bone of the ossicular chain.

Induction coil:

The telecoil inside of a hearing aid that is activated by electromagnetic energy coming from a telephone or assistive listening device.

Impulse sound management:
Isolates sudden, high-pitched sounds and brings them down without affecting normal sound ranges.

Induction loop system (loop):

The broadcasting end of a system that enables hearing aid users that have a Telecoil, to hear sounds projected in theaters, cinemas, auditoriums or other venues, that are equipped with an induction loop system.


Also known as the cochlea. The snail-like portion of the ear system that converts mechanical sound energy coming from the middle ear into an electrical impulse prior to transmission to the brain.

Insertion gain:

The difference between the amount of intensity present at the eardrum when a functioning hearing aid is in an ear and turned on versus the amount of intensity present when there is no hearing aid in the same ear.


In place. The in-situ gain of a hearing aid is measured with the hearing aid in place in the ear.

ITE (In-the-ear) hearing aid:

Refers to all hearing aids that are pleased inside the ear, from the conchaL bowl to inside ear canal, without having wires or components connecting to other hardware, this category includes ICC, IIC, half shell, full shell and other Inside the ear hearing aids.

ITC (In-the-canal) hearing aid:
A hearing aid that fits inside the ear canal, it normally has a part of it sitting inside of it and a small part of the shell showing in the canal opening.

K-AMP Circuit (TILL):
A circuit designed to increase at low levels and to decrease at high levels. Named after its inventor, Dr. Mead Killion, this circuit is designed to amplify more in quiet environments and less in loud ones. It's normally used in soft sounds amplification devices or programs, the circuit regulates the frequency volumes automatically.


The hollowed-out area of the skull’s temporal bone that contains the cochlea and parts of the balance system.

Limiting compression circuits:

A circuit that automatically limits gain (volume) as the sounds enter the microphone. This circuit is used in hearing aids for patients who have mild to severe hearing loss.

Linearity is the behavior of a circuit, particularly an amplifier (speaker), in which the output signal strength varies in direct proportion to the input signal strength. This basically means that the volume of the speaker will increase the volume of the sound getting to the microphone increases as well.

Listening stethoscope:

A device used that allows hearing healthcare professionals to listen to a hearing aid for the purpose of assessing the hearing aid’s performance and adjustments/repairs.


The ability of the brain to determine the direction from which the sound originated by utilizing differences between the timing and intensity of a sound as perceived in one ear compared to the other ear.

The first/hammer-shaped bone in the ossicular chain, that is attached to the eardrum.

Masking noise:

A sound introduced into an ear system for covering up an unwanted sound. Masking noises are used during hearing tests to cover-up unwanted responses from a non-test ear. Tinnitus maskers also utilize a masking noise to cover-up tinnitus.

Mastoid bone:

A portion of the temporal bone that is located behind the external ear. The bone conduction vibrator employed during bone conduction testing is usually placed on the mastoid.

Meniere’s Disease:
A name applied to a set of symptoms (usually including vertigo, hearing loss, and tinnitus) that results from an overproduction of fluid in the endolymphatic sac of the inner ear (hydrops).

The entry point for sound into a hearing aid. The mechanism inside a hearing aid that converts sound waves into an electrical signal.


A congenital malformation of the external ear. A condition in which an individual is born with an abnormally small pinna and often a very small or absent ear canal.

The portion of the human auditory system located between the outer and inner ear, which uses the tympanic membrane (eardrum) and ossicles (malleus, incus, and stapes) to transfer the sound via vibration from the ear canal to the cochlea.

Middle-ear effusion:

When the body discharges fluid into the middle ear cavity.

Mixed hearing loss:
A hearing loss that has both conductive and sensorineural components.

Refers to when sound is presented only to one ear.

Most comfortable level (MCL):
A measurement that is often made prior to the ordering of or programming of a hearing aid that determines, for speech or tones, the intensity level that a patient considers to be the most acceptable in regards to the overall comfort of the signal.

Multi-band hearing aid:
A programmable hearing aid that allows the dispenser to adjust gain in a specified set of frequencies without affecting gain at other frequencies.

Multi-channel hearing aid:
A programmable hearing aid that allows the dispenser to adjust the instrument’s compression characteristics in a specified set of frequencies without affecting the compression characteristics at other frequencies.

Multi-memory hearing aid:
A hearing aid that has more than one dispenser adjusted listening program that the patient can access to improve communication in various environments (i.e., memory one for normal listening, memory two for noisy environments, and memory three for telephone use).

Noise-induced hearing loss:
A type of hearing loss caused by the introduction of intense volumes into a human ear system over long periods of time or very intense volumes for a short period of time. The hearing loss often is worse on the side of exposure and is most pronounced in the higher frequencies.

The sensation that results from “plugging up” the ear canal with earwax, an un-vented hearing aid, or a foreign body.

Occupational hearing loss:
The hearing loss associated with the exposure to loud sounds in a work environment.

On-the-ear (OTE)/Open-ear hearing aid:

A more recently developed style of a BTE hearing aid that utilizes a thinner tubing and a placement of the electronics lower down behind the ear for better cosmetic appeal with less occlusion.

A class of hearing aids that do not occlude the ear canal.

Organ of Corti:
The structure built upon the basilar membrane inside of the spiral cochlea that contains the special sensory receptors (hair cells).

Ossicular chain:

The three very small bones located in the middle ear that is connected and form a link between the tympanic membrane (eardrum) and the cochlea. The three ossicles called the malleus, incus, and stapes (hammer, anvil, and stirrup), transfer the sound through the middle ear via vibrations.


Feedback. The whistling that hearing aids can emit when an amplifier becomes unstable.


A device that is used to produce vibrations, such as the bone conduction oscillator used during bone conduction threshold testing.


Ear pain or an earache.Otitis: Inflammation and/or infection of the middle ear.


An Ear, Nose, and Throat (ENT) physician.


An ENT physician who specializes in the evaluation and treatment of the ear.


A magnifying and lighting tool utilized by health care workers to look into the ear canal.

Ototoxic Medications:

Prescription or over-the-counter drugs that can have a temporary or permanent detrimental effect on an individual’s hearing or balance system.


The most peripheral aspect of the human auditory system that includes the auricle (pinna) and external auditory meatus (ear canal).

Perforated tympanic membrane:

A hole in the eardrum.

Peripheral hearing loss:
Hearing loss due to a dysfunction of the auditory structures located outside of the central nervous system.

Personal Sound Amplifier (PSAPs):
An electronic device that amplifies all sound. A PSAP is not a hearing aid. PSAPs are not tailored to an individual's hearing loss and can be purchased without a prescription. 

P.E. Tubes:

Pressure equalization tubes placed into the tympanic membrane (eardrum) for the purpose of keeping pressure levels in middle ear cavity equal to atmospheric pressure.


Also referred to as the auricle. The cartilaginous structures of the external ear located peripheral to the skull.

Power BTE (Power Behind-the-ear hearing aid):

A hearing aid designed specifically for individuals with severe to profound hearing losses to provide the appropriate amount of extra gain needed to match their specific losses.

Pre-lingual hearing loss:

Hearing loss that occurs prior to a child developing speech and language skills.


A Sensorineural type of hearing loss related to aging.

Programmable hearing aid:
A helpful feature on more current hearing aids that allows them to be attached, via a cord, to a computer in a hearing healthcare professional’s office or via a wireless connection. Once connected, they can be “programmed” to various parameters that apply to the patient’s hearing loss and communicative needs. More expensive hearing aids tend to have more parameters available for adjustment than less expensive hearing aids, often making them more adaptable.

Real ear:
A measurement made with a dedicated piece of equipment (real-ear analyzer) that shows the performance of a hearing aid while present in the user’s ear.

Receiver (Speaker):

The speaker inside a hearing aid that converts the amplified electrical energy to sound waves.

Rechargeable hearing aid:

A hearing aid that contains a rechargeable battery, these can be exchangeable rechargeable batteries (can be adapted to a traditional hearing aid) or contain a closed compartment inaccessible to the user, the later ones normally are connected to a rechargeable station or cable.

A condition often occurring with a sensorineural hearing loss that results in an abnormal growth in loudness. For someone with hearing loss who experiences recruitment, a specific increase in intensity is perceived as a significantly larger increase in loudness than a normal hearing individual would perceive the same increase in intensity.


A designation for the part of the human auditory system that includes the acoustic nerve, the brainstem, and the brain.


The interference noted when an individual hears sounds “bounce” around the inside of a room.

RIC (Receiver-in-canal):

Refers to the types of hearing aids that have the receiver (speaker) outside of the hearing aid’s case, connected through a cable. The receiver can be placed inside the canal (RIC) or using a custom mold (RITE).

RIC (Receiver-in-canal):
Refers to the types of hearing aids that have a receiver (speaker) attached through a cable to the rest of the hearing aids hardware, they sit behind the ear, but differ from the Behind the ear (BTE) types, in that the speaker is outside of the hearing aids case, placed inside the canal.

RITE (Receiver-in-the-ear): 
Similar to the RIC hearing aid, only the receiver/speaker sits on the outer ear (instead of inside the canal) using a generic or custom mold similar to the ITC (In-the-canal) hearing aids.

Semicircular canals:

The three fluid-filled tubes in the vestibular portion of the inner ear that helps with equilibrium and the interpretation of the body’s position.

Sensorineural hearing loss (SNHL):
A decrease in an individual’s ability to hear a sound due to a problem in the inner ear (cochlea) or the neural system (Cranial Nerve VIII). The designation of a hearing loss as sensorineural suggests that the sound makes its way through the outer and middle ear systems efficiently, but is not picked-up by the hair cells in the cochlea or transmitted by the hearing nerves as well as an average normal human ear’s system.

Signal-to-noise ratio:
The relationship between the intensity of the desired sound (signal) and other undesired sounds (noise). The louder the speech signal is presented in comparison to the background noises, the better chance a person has at understanding the speech signal.

Speech Audiometry:

The portion of an audiological evaluation that uses speech stimuli to measure the auditory system. Speech audiometry testing often includes the measurement of Speech Reception Thresholds (SRTs) utilizing two-syllable spondee words and the assessment of Word Recognition / Speech Discrimination Scores utilizing single syllable words in a carrier phrase. Some speech audiometry tests use sentence materials instead of single word materials.

Speech mapping:

A variation of the traditional real ear analysis, during which a professional uses a special device to measure the performance of a hearing aid using speech as the input instead of a series of tones.

Tele (T-coil):
A small wire coil placed inside of a hearing aid used as an antenna allowing the hearing aid to receive wireless signals. When activated, the hearing aid will turn off the microphone(s) in the hearing aid and transmit only the signal transmitted through the Telecoil.


The sensation of noise or constant ringing in the ears when an external sound is not present. This condition happens when the sensory organs in the ear send sound signals to the brain by mistake. In many cases, there is a strong relationship between hearing loss and Tinnitus.

A switch or button on a hearing aid that allows the user to change memory settings or programs in the hearing aid to adapt to different environments (Dinner, Home, Office, etc.)


The portion of a CROS system that picks up a signal on one side of the head and sends it via a hard wire or an FM signal to the receiver on the other side of the head.

Tympanic membrane:
Another name for an eardrum. It is the membrane that separates the ear canal and the middle ear cavity. The tympanic membrane vibrates when hit with sound waves, causing the ossicular chain to vibrate.

Uncomfortable loudness level (UCL):

A measurement that is often made prior to the ordering of or programming of a hearing aid that determines, for speech or tones, the intensity level at which a patient judges a signal to be uncomfortably loud.

Pertaining to only one ear or one side of the head (i.e., The person with a hearing loss on the right but not the left has a unilateral hearing loss.).


A hole placed in a hearing aid or earmold to modify the amount of occlusion effect noted by a hearing aid wearer or to adjust the frequency response of the hearing aid.


A sensation of spinning experienced by individuals with vestibular problems.

Vestibular system:

The inner ear portion of the balance system.

Volume control:

A feature on a hearing aid, on a remote control connected to the hearing aid or in an external application (phone, computer) utilized by a hearing aid wearer to increase or decrease the instrument’s gain.

(see cerumen) 

Wax loop:
A small tool used by professionals and hearing aid users to clean ear wax out of the tubing of a hearing aid.

Word recognition score:
The percentage of a list of speech stimuli that an individual can repeat back during an evaluation.

Stay in the loop.

Subscribe here for more information on the latest hearing aid technology and hearing loss treatment.

Our privacy policy