Acoustic feedback: Unpleasant whistling or squealing noise that others can hear - created when sound amplified by a hearing aid gets picked up by its microphone.

Air conduction: The passing of sound into the inner ear through the outer ear and middle ear.

Anvil: See 'Incus'.

Assistive listening device: A type of equipment, other than a hearing aid, that provides amplified sound to a hearing impaired person.

Audiogram: A chart or graph showing a person's ability to hear different pitches (frequencies) at different volumes (intensities) of sound in each ear.

Audiologist: A health care professional trained to evaluate and manage hearing loss and related disorders, including balance (vestibular) disorders and tinnitus.

Audiometer: A machine used to test hearing.  Basic screening audiometers give an indication of how well someone can hear.  Diagnostic audiometers, found in most audiology departments, are able to provide a better picture of hearing ability - including the type of hearing loss.

Auditory nerve: The a nerve in the ear that carries nerve impulses from the cochlea to the brain.  It is also sometimes referred to as the cochlear nerve, or the VIIIth nerve.


Baha®: A special type of hearing aid that has a permanent physical connection to the bones of the skull.

BiCROS (hearing aid): A variation of the CROS hearing aid, for use by people who have a profound hearing loss in one ear as well as a significant loss in the other ear. A microphone picks up sound from behind the ear with the greater hearing loss and sends the signal (via a wire or by wireless technology) to a hearing aid worn on the better ear. 

Bilateral hearing loss: A hearing loss in both ears.

Body Worn hearing aid: A hearing aid in which a small box is clipped on to clothes or put in the pocket. This box contains the microphone and working parts. It is connected by a lead to an earphone clipped into your earmould. Body-worn hearing aids may be suitable for people with sight problems, or problems using very small switches or buttons. 

Bone conduction: Sound that is transmitted by, and heard through, the bones of the skull.


Cerumen: See 'Ear wax'

Cochlea: The snail-shaped structure within the inner ear where sound vibrations are converted into nerve impulses.

Cochlear implant: A type of hearing device in which electric currents corresponding to the sound signals that a person wants to hear are passed straight to the sensory cells of the inner ear (cochlea) via a surgically implanted electrode.

Conductive hearing loss: A type of hearing loss resulting from sound not reaching the inner ear properly. Conductive hearing loss happens when there is a problem conducting sound waves through the outer ear, tympanic membrane (eardrum) or middle ear (ossicles). This type of hearing loss can occur together with sensorineural hearing loss or alone.

CROS (hearing aid): A special type of hearing aid, made up of two parts, for use by people with a unilateral hearing loss. A microphone picks up sound from behind the ear with the hearing loss and sends the signal (via a wire or by wireless technology) to a hearing aid worn on the other ear.  See also: 'BiCROS (hearing aid)'


DECT phone: A landline telephone in which the base unit is connected by wire to a standard telephone socket but by radio signals to the handset, enabling it to be carried around the home. 

Decibel: Widely used in sound measurement (abbreviated to dB). Strictly speaking, a decibel rating relates to the ratio of the strength of a particular sound to a standard reference level, but in practicval terms, it is used as an unit.


Ear canal: The passage that leads from the outer ear (pinna) to the eardrum.

Ear drum: See 'Tympanic Membrane'

Earmould: A contoured ear fitting used to feed the sound output from a hearing aid into the ear. Earmoulds are usually custom-made in acrylic to fit a particular ear, but occasionally may be made of other (sometimes non-allergenic) materials.

Ear wax: A yellowish waxy substance produced in the ear canals which plays an important role in the natural cleaning and lubrication of the outer ear.

Eustachian tube: The short tube connecting the back of the nose to the middle ear which equalises the air pressure on both sides of the ear drum.


Feedback: The high-pitched whistling sound caused by the hearing aid's microphone picking up the output of the hearing aid and re-amplifying it.  Well fitted earmoulds can eliminate the problem of feedback.

Frequency: The number of vibrations of a sound wave in one second, measured in Hertz (Hz).


Hair cells: The sensory cells of the inner ear, which are topped with hair-like structures (called stereocilia) which convert sound energy into nerve impulses.

Hammer: See 'Malleus'

Hearing Aid:An electronic device that amplifies sound. They are usually worn behind or inside the ears by people with a hearing loss.

Hearing Aid Council (HAC): The Government body that regulates the private hearing aid market. All hearing aid dispensers in the UK must be registered with the HAC and meet their standards of education, training and conduct.

Hearing aid dispenser: A professional employed in the sale and fitting of hearing aids. In the UK, hearing aid dispensers must be registered with the Hearing Aid Council .

Hearing loss: A full or partial decrease in the ability to detect or understand sounds.

Hearing threshold: The minimum sound level of a pure tone that an individual is able to hear in a noiseless environment. In audiology, hearing thresholds are tested at a number of different frequencies.


Impression:A moulded replica of the outer ear which is created by the audiologist and used as the basis for creating personalised earmoulds

Incus: One of the small bones or ossicles of the middle ear.  The incus transmits sound vibrations from the malleus to the stapes.  The word is Latin for 'anvil'.

Induction loop: A complete circuit (loop) of wire through which an electric current corresponding to a sound signal is passed.  The current causes the generation of a magnetic field, which can be received on a hearing aid set to 'T'.

Inductive coupler: A very small induction loop incorporated in a product such as a telephone that enables it to be used with a hearing aid on the 'T' (telecoil / loop) setting.

Inner ear: The part of the ear that converts sound vibrations into neural messages that are sent to the brain.  The inner ear contains the cochlea.


Lip reading: A way of understanding speech by visually interpreting the movements of the lips, face and tongue of the speaker, along with other information provided by the context, language, and any residual hearing.

Localisation: Refers to a person's ability to identify the location or origin (in terms of distance and direction) of a detected sound.


Malleus: One of the small bones or ossicles of the middle ear which connects with the incus and is attached to the inner surface of the ear drum. The word is Latin for 'hammer'.

Mastoid bone: The area of bone directly behind each ear.

Ménière’s disease: An inner ear disorder than can affect both hearing and balance.  The disease is characterised by episodes of dizziness and tinnitus, as well as a fluctuating hearing loss.

Middle Ear The air-filled cavity containing the ossicles and tympanic membrane, the function of which is to transfer sound energy from the outer ear to the inner ear.  The middle ear is connected to the back of the nose by the Eustachian tube.


Ossicles: The three tiny bones (the smallest in the human body) that transmit sound from the eardrum across the middle ear cavity to the round window (entrance) of the cochlea.

Otosclerosis: A condition in which there is abnormal growth of bone in the middle ear, resulting in a conductive hearing loss.

Otoscope: A small torch-like instrument used for looking into the ear canal.

Outer ear: The part of the ear visible externally (the pinna), as well as the ear canal. Its function is to collect sounds and deliver them to the middle ear.

Oval window: The membrane covered opening to the cochlea, to which the stapes is attached.

Ototoxic drugs: Drugs that can damage the inner ear, particularly the sensory hair cells within the cochlea.


Pinna: The visible part of the ear, outside of the head (also referred to as the auricle).

Pitch: The subjective perception relating to the physical frequency of sound.

Presbycusis: The natural, gradual loss of hearing which is the result of the ageing process.  Also known as 'age related hearing loss'.

Pure Tone Audiometry: Pure tone audiometry (PTA) is the most widely used hearing test for identifying hearing threshold levels and enables the determination of the degree, type and configuration of a hearing loss. The test is carried out using an Audiometer.


Real Ear Measurements (REMs):

Relay service: An operator service that allows people who are deaf or hard of hearing to place calls to standard telephone users via a keyboard or assistive device


Sensorineural hearing loss: A hearing loss associated with the 'sensory' part of the hearing system, that is the inner ear (cochlea) and auditory nerve.

Sign Language: A form of language used by deaf and hard of hearing people which uses visible hand gestures rather than voice to convey meaning. 

Stapes: A small stirrup-shaped bone of the middle ear that transmits sound from the incus to the cochlea.  The Stapes is the smallest bone in the human body.

Stirrup: (See 'Stapes')


Tinnitus: The sensation of noise within the ear or head when there is no external sound source.  The noise heard differs from person to person, but is often described as a ringing, buzzing or roaring sound.  Tinnitus is often associated with many forms of hearing loss and noise exposure.

Telecoil: The part inside a hearing aid designed for use with an induction loop

Tinnitus relaxer: A sound enrichment device that can help to relieve tinnitus through relaxation.

Tympanic Membrane: The thin membrane that separates the outer ear from the middle ear. Its function is to transmit sound from the air in the outer ear to the ossicles inside the middle ear.

Tympanometer: A machine used by audiologists and ENT doctors to measure the ability of the middle ear to allow sounds to pass through and into the inner ear.



Unilateral hearing loss: A hearing loss in one ear only.


Vestibular System: The system in the inner ear that is concerned with controlling balance.


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