Acute otitis media (AOM):

Middle ear inflammation of relatively sudden onset; indicated by a bulging red ear drum and pain

Acquired hearing loss:

Hearing loss obtained after birth (not congenital). Noise, disease, viruses, ototoxic drugs and the aging process are all possible causes of an acquired hearing loss.


The amplifier, which is an important electronic component of the hearing aid, electronically increases the intensity of sound energy. The amplifier obtains an electronic signal from the hearing aid microphone and sends the boosted signal to the hearing aid’s receiver.

Analog sound processing:

Describes a method by which sound passes through a hearing aid in fluctuating voltages. Analog hearing aids constitute a very small minority of the hearing aid market and are typically not software programmable. Analog sound processing typically does not have the operating speed to allow advanced and automatic features such as automatic program switching or automatic feedback management.

BTE (Behind-the-Ear):

A BTE is a hearing aid style with two main parts. First, is the body of the instrument which discreetly sits behind the ear. The second part is the earmold, which is attached to the body of the BTE and sits securely in the ear canal.


Also known asearwax, cerumen is a protective and lubricating substance generated in the ear canal. Occasionally enough earwax is produced to completely fill or occlude the ear canal.

CIC (Completely–In–The–Canal):

A CIC is the smallest hearing aid style available. This style of hearing aid is most suitable for mild to moderate hearing losses and is custom–made to fit deep inside the ear canal.


The cochlea is in the inner ear. It resembles the circular shell of a snail and houses a system of tubes filled with a watery liquid as well as tiny hair cells. When the hair cells move because of incoming sound vibrations, the sound is transformed into electrical signals that can be interpreted by the brain.

Conductive hearing loss:

A conductive hearing loss is due to a problem in the outer or middle ear that makes it difficult for the sound to reach the inner ear. It can be both temporary and long–term. The most common causes of a conductive hearing loss can be a build–up of wax in the ear canal, a perforated eardrum, fluid in the middle ear (which is common in children) or damage to the middle ear bones (the ossicles).

Congenital hearing loss:

A hearing loss present at birth. Congenital hearing losses can be hereditary, due to an infection or disease during pregnancy, or even due to birth complications. The causes of some congenital losses are not known. Congenital hearing losses can be sudden or delayed in onset.

Cued speech:

A system of hand shapes used to supplement the information received from speech reading (lip–reading). Cued speech is sometimes used by patients with severe profound hearing loss.


A hearing aid that has been built for one individual. Typically, a custom–made hearing instrument has an earmold or casing that has been crafted to fit only one particular individual.


Having little or no functional hearing ability. Deafness can be congenital (from birth) or acquired (later in life).

Degree of Hearing Loss:

Generally, the degree of hearing loss (HL) is described using one of five categories:

Mild (average from 25–40 dB HL)

Moderate (average from 41–55 dB HL)

Moderately-Severe (average from 56–70 dB HL)

Severe (average from 71–90 dB HL)

Profound (average greater than 90 dB HL)

Hearing loss is defined based on what a hearing–impaired person can and cannot hear.

Digital sound processing:

The most common type of sound processing. A term that describes the method by which sound passes through a hearing aid. With digital sound processing, sound is converted into mathematical bytes of computer information that allow sound to be processed at ultra–high speed. The result is that sound quality is better reproduced and advanced hearing aid functions such as automatic program switching and feedback cancellation are more easily performed.

Directional Microphone:

A hearing aid component consisting of 2 or more microphones and whose purpose is to enhance some sound locations more than others. For example, the intended purpose of a directional microphone is to help a hearing aid wearer function better in background noise by amplifying the space in front of a hearing aid wearer more than the space behind the hearing aid wearer.

Ear canal:

The part of the ear through which sound is transmitted to the middle ear.

Eardrum: Also called the tympanic membrane, it is a nearly transparent layer of skin at the inner end of the ear canal about 1 1/2″ into the skull. The eardrum abuts to other parts of the hearing system. The eardrum reacts to incoming sounds by moving inward and outward and helps pass sounds picked up by the outer ear to continue on the pathway to the brain where sound is analyzed and interpreted.

Earmold: An earmold is a coupling device that is molded to fit into the human outer ear and is connected, via plastic tubing, to the earhook of a behind–the–ear hearing aid. It is often made of hard clear acrylic or more pliable materials. For hearing aid wearers, sound then enters the hearing aid and passes through the earmold and into the human ear canal.

Earwax:See cerumen.

Eustachian tube:

This tube connects the middle ear cavity to the nose and throat. Its purpose is to keep the middle ear space at normal atmospheric pressure. Eustachian tube dysfunction is a common cause of middle ear disorders such as fluid in the ear.


Sometimes described as a squealing or whistling type of annoying noise, one common type of feedback is a sound that sometimes appears when a hearing aid wearer does not have the hearing aid properly placed in the ear. An incompletely sealed hearing aid allows sound that has already been amplified by the hearing aid to escape.

Feedback Cancellation:

A feature common on many modern hearing aids that reduces or eliminates feedback with minimal effect on the sound quality of the hearing aid.

Fitting software:

Fitting software is a set of computer instructions that a licensed hearing care professional uses to program hearing aid/s for the individual hearing aid wearer. The purpose of fitting software is to allow the hearing care professional to obtain the best possible outcome. Fitting software is usually not interchangeable between different brands of hearing aids and not intended to be used by an unlicensed person.

FM listening systems:

FM listening systems are usually considered an assistive listening device (ALD), a supplementary device that often works and connects to a hearing aid system. An FM system has a microphone/transmitter that is placed on or near a chosen listening area or on another person. The FM microphone/transmitter sends the sound being picked up to a FM receiver worn by a hearing aid wearer. The FM receiver is connected to the hearing system enabling the hearing aid wearer to hear the microphone/transmitter up to a distance of 150 feet or more in some instances.


A term used most often in the field of hearing and acoustics that expresses the repetition of sound waves per second. A common synonym for frequency is “pitch.” Lower frequency sounds are lower pitched sounds. Higher frequency sounds are higher pitched sounds.

Hard of hearing:

The term used to describe a degree of hearing loss ranging from mild to profound for which a person usually receives some benefit from the amplification provided by hearing aids.

Hearing Aid:

An instrument that amplifies sound to assist persons with hearing loss. They are distinguished by where they are worn: in the ear (ITE), in the canal (ITC), completely in the canal (CIC), behind the ear (BTE), or on the body.

Hearing Loss:

The difference between the level of sound that can just be heard by an individual with impaired hearing and a standard level that has been determined by averaging measurements from a group of young hearing adults. It is usually expressed in decibels.

Hertz (Hz):

Hertz is the unit measurement of frequency (pitch) of sound. It’s determined by the number of cycles of a sound wave in one second. High–pitched sounds, such as a police whistle, have a high frequency with thousands of cycles per second. Low–pitched sounds, such as far away thunder, have a low frequency with only a few cycles per second.


Commonly called the “anvil.” The incus is a small bone, which is the second of the three bones (ossicles) work in series in the middle ear to transmit sound to the inner ear.

Inner ear:

That part of the ear, particularly the cochlea, that converts mechanical vibrations (sound) into a neural signal recognized by the brain.

ITE (In–The–Ear):

ITE hearing aids are custom–made to fit the individual user’s ear. As the word explains ITE hearing aids are worn inside the ear and are usually recommended for mild to moderate, or sometimes even severe hearing losses. ITE hearing aids come in several sizes, but they are not usually recommended for young children, because their outer ears and ear canals are still growing.

Lip reading:

The ability to understand what is being said by watching a speaking person’s lips as well as their face, expressions, and gestures.


The loudspeaker is a part of a hearing aid that’s also called the receiver. It receives the amplified electrical signal and changes it into an acoustical signal that the user of the hearing aid can hear.


Also known as the “hammer.” A small bone in the middle ear that helps transmit sound vibrations from the eardrum to the incus.


The part of a hearing aid that leads sound into the amplifier to be processed. It changes acoustical energy into electrical energy, which is then processed within the hearing aid.

Middle Ear:

That part of the ear that conducts sound to the inner ear, consisting of the eardrum (tympanic membrane), middle ear bones (ossicles), and the cavity containing them.

Mixed hearing loss:

A mixed hearing loss occurs when there’s a problem in the inner ear and outer or middle ear. It’s a combination of a conductive and sensorineural hearing loss.


The general meaning of noise is any unwanted sound.

Non–programmable hearing aid:

The sound of a non–programmable hearing aid can be adjusted on one or more variable potentiometers (or trimmers) on the hearing aid with a tiny screwdriver. The trimmers can typically adjust the low frequencies (bass) and the high frequencies (treble) and the maximum output of the hearing aid.

Open Canal Hearing Aids:

A hearing aid in which the human ear canal is minimally closed off using a non-custom earmold to the ear and a small BTE instrument.


Ossicles are bones. In ear anatomy, the 3 ossicles (the malleus, incus, and stapes) are located next to the eardrum deeper in the skull within the middle ear. The ossicles are important in that they help pass the motion of sound created by eardrum movement on to the inner ear with a minimal loss of loudness.

Otitis media (OM):

Literally, an inflammation of the middle ear, usually due to a failure of the Eustachian tube (at the base of the middle ear) to properly open and close. If the Eustachian tube fails to open and close, middle ear fluid may accumulate in the middle ear. In some instances, the fluid may become bacteria–infected. Otitis media is a common childhood disease.

Otolaryngology:(pronounced oh/toe/lair/in/goll/oh/jee)

Otolaryngologists are physicians trained in the medical and surgical management and treatment of patients with diseases and disorders of the ear, nose, throat (ENT), and related structures of the head and neck. They are commonly referred to as ENT physicians.


A condition in which the bones of the middle ear become immobile because of bony growth. Otosclerosis results in a conductive hearing loss.


Medications, caustic agents or drugs that can damage hearing. Ototoxicity can result in either a permanent or temporary sensorineural hearing loss.

Oval window:

The oval window is the junction between the middle ear and the inner ear. It contains the footplate of the stirrup, which act like a piston moving the fluids in the cochlea, an important part of the transmission of sound through the auditory system.


Portion of the outer ear protruding from the head; also called the auricle. The primary function of the pinna is localization of sound.


Hearing loss associated with the aging process. Presbycusis is a type of acquired hearing loss that is gradual in onset.

Programmable hearing aid:

A digitally programmable hearing aid is programmed via computer or a handheld programming device.

Residual hearing:

The hearing ability remaining in a hearing–impaired person.

Sensorineural hearing loss:

One of several types of hearing loss, sensorineural hearing loss occurs when the nerve cells of the hearing organ of the inner ear, the cochlea, are damaged. The result is almost always permanent, irreversible, and can increase over time. Common causes for sensorineural hearing loss include the aging process and exposure to excessively loud sound/s. The use of hearing aids is frequently successful in sensorineural hearing loss.

Semicircular Canals:

The organ of balance connected directly to the cochlea in the inner ear.

Sign language:

Form of manual communication in which words and concepts are represented by hand positions and movements.

Sound level:

A general term expressing the intensity or loudness pressure of a sound in decibels (dB).


The third of the three middle ear bones, also called the “stirrup”. The stirrup transmits the sound vibrations via the oval window to the inner ear fluids. The stapes is the smallest bone in the body.

Threshold of Hearing:

The softest sound level of intensity or loudness that produces the sensation of hearing perception. Threshold of hearing increases with increased hearing loss.

Tympanic membrane: See eardrum.


An optional small opening or tunnel in a hearing aid shell or earmold running from the outside portion to tip end. The purposes of venting may include providing comfort (pressure relief/fresh air exchange) for the ear canal, or manipulating hearing aid performance by allowing certain sounds to pass through or out of the vent.