Auditory Brainstem Response. This is a test performed on children by placing electrodes on the child’s head and measuring the electrically generated waves from the cochlea via the auditory nerve. The result can help tell whether there is a hearing loss in the inner ear or a problem with the auditory nerve.

Hearing loss obtained after birth (not congenital). Noise, disease, viruses, drugs or the simple process of ageing can cause an acquired hearing loss.

The amplifier constitutes the electronics of the hearing instrument and consists of various pieces of circuitry. The amplifier processes the signal from the hearing instrument’s microphone according to the settings that have been prescribed.

The Anvil is the common name given to the second of the three small bones (ossicles) in the middle ear, that work together to transmit sound to the inner ear. Also see under H (Hammer, Anvil and Stirrup).

The most common assistive listening device is FM solutions , however, there are also devices such as a telephone amplifier or remote doorbell, which can help in situations where you have difficulty hearing – either because of background noise or because sounds come from far away.

Audiology is the science of hearing. An audiologist is a professional trained to evaluate hearing loss and prescribe, fit and adjust hearing instruments and assistive listening systems.

This is the auditory section of the central nervous system. This nerve transmits the auditory information to the brain.

Behind-The-Ear instruments are suitable for all types of hearing losses from mild to profound. The amplified sound is transmitted from the hearing aid through a clear plastic tube to an earmould, which is custom-made to fit your child's ear, to look and feel just right. The sound is directed into the child's ear canal.

BTE instruments are most often recommended for children because this style is exceptionally sturdy, and is not limited by the size of the child’s ear.

A CIC is the smallest hearing aid style of hearing instrument available. CIC stands for “Completely In the Canal”. This style of hearing instrument is suitable for mild to moderate - sometimes even severe - hearing losses, and is custom-made to fit deep inside the ear canal. Most children do not have large enough ear canals to use this style of instrument.

The cochlea is 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, the sound is transformed into electrical signals that can be interpreted by the brain.

A Conductive hearing loss is caused by a problem in the outer or middle ear which 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).

Having a congenital hearing loss means that the hearing loss is 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.

This means that an impression is taken of the child’s ear to ensure that the ear mould (or ITE hearing instrument) fits the child’s ear canal exactly, thereby avoiding feedback or irritation.

Decibel Sound Pressure Level expresses the sound pressure level relative to 20 micro Pascal (µPa). 20 µPa at 1 KHz is the weakest sound level a person with normal hearing can hear. Sound pressure at 20.000 µPa is equivalent to 60 dBSPL, which is where you hear normal speech.

Feature

DFC can prevent feedback arising from slow and gradual changes in the feedback path, e.g., a growing ear canal or eamold shift during daily activities. In addition, feedback arising from abrupt changes in the acoustical environment, e.g., parents hugging their child or holding a phone to the ear can be eliminated.

Benefit
Feedback is eliminated with minimum gain reduction and distortion. This ensures consistent audibility throughout the day as well as good sound quality.

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

An ear mould is used with BTE hearing instruments. The amplified sound is sent via tubing to the ear mould, which is inserted into the ear canal.
The ear mould is made using an impression of the user’s ear to ensure that it fits perfectly.

When sound waves enter the outer ear they travel through the ear canal. At the end of the ear canal the sound waves reach a cone-shaped membrane – the eardrum. When the sound hits the eardrum it vibrates – just like a real drum.

This tube connects the middle ear cavity to the nose and throat, and its purpose is to keep the middle ear space at normal atmospheric pressure. A common cause of middle ear disorder is Eustachian tube dysfunction.

Feedback is the loud, unpleasant, high-pitched whistling which can sometimes be heard from hearing instruments. It occurs when the amplified sound re-enters the hearing instrument and is re-amplified.

The audiologist will fit a hearing instrument to match the individual user’s needs, using fitting software. All digital instruments are adjusted via a computer.

FM solutions work by picking up the sound of a speaker’s voice through a microphone and transmitting it as a radio signal directly to the person wearing the hearing instrument. FM systems are valuable when there is a lot of noise present or when there is distance between the speaker and the listener - situations which typically make speech understanding very difficult for someone with hearing loss. This could be in school, in a car, at a noisy playground or in the home.

The number of times a repetitive event occurs in a specified time period is a frequency. For the sinusoid waves shown it is the number of periods occurring in one second. This is expressed in cycles per second or Hertz (Hz). A common word for frequency is pitch.

These three bones, which are also called the ossicles, are the tiniest bones in the human body. When sound waves make the eardrum vibrate, these vibrations are continued by the movement of the ossicles. The innermost of the ossicles (the stirrup) moves and creates motion in the fluid of the cochlea.

Hertz is the unit measurement of frequency (pitch) of sound. The number of cycles of a sound wave in one second (cycles per second) is more commonly specified in Hertz (Hz). High-pitched sounds, such as a police whistle, have a high frequency with thousands of cycles per second. Low-pitched sounds, such as distant thunder, have a low frequency with only a few cycles per second.

ITE – or In-The-Ear – hearing instruments are custom-made to fit the individual user’s ear. As the word indicates, ITE hearing instruments are worn inside the ear and are usually recommended for mild to moderate or sometimes even severe hearing losses. ITE hearing instruments come in several sizes, but they are not usually recommended for young children, because their outer ears and ear canals are too small, and are still growing. If they are suitable for your child's particular hearing loss, he or she can typically wear them from about the age of 8-10 onwards.

Hearing is a sense that involves not only the loudness and pitch of sounds, but also distance or range. A child with a hearing loss will have a reduced hearing range, or a smaller listening bubble, than a child with normal hearing. When you are in another room, you are using your hearing range, or have a listening bubble that includes hearing sounds of that loudness, frequency and distance. People with hearing loss have smaller listening bubbles.

The loudspeaker is also called the receiver. It receives the amplified electrical signal and changes it into an acoustical signal that the hearing instrument user can hear.

The microphone leads the sounds into the amplifier for processing. It changes acoustical energy into electrical energy, which is then processed within the hearing instrument.

Generally, the degree of a person’s hearing loss is described using one of five categories:

• Mild (average from 25-40 dB HL)
• Moderate (average from 40-55 dB HL)
• Moderate/Severe (average from 55-70 dB HL)
• Severe (average from 70-90 HL)
• Profound (average greater than 90 dB HL)

The hearing loss is defined based on what the person can and cannot hear. You can refer to the following audiogram where A = Hearing level in decibels (dB) and B = Frequency in Hertz (Hz)

Otoacoustic Emissions. This is the most common newborn hearing screening test. By sending sound into the ear the response from the inner ear is measured to determine whether a hearing loss is present.

Hearing instruments or earmoulds can make you feel blocked up – as if you are sitting inside a barrel. This is referred to as the ‘occlusion-effect’. To get an idea of what occlusion is, put a finger into each ear while talking or eating. If you slowly remove your fingers, the sounds will become more and more pleasant, as the occlusion effect disappears.

The oval window is the junction between the middle ear and the inner ear. It contains the footplate of the stirrup, which acts like a piston, moving the fluids in the cochlea.

See Mild to Profound under M

A rationale is the mathematical formula upon which the calculations for amplification are made, depending on the nature of the hearing loss. The rationales are typically based on experiences from thousands of users, and they provide an excellent starting point in the hearing instrument fitting. The rationale called DSL is the one most often used with children. It is developed at the University of Western Ontario in Canada – a university with many years of experience within paediatric audiology.

RECD is short for Real Ear to Coupler Difference. These are the correction factors that accommodate the acoustical differences between a child’s smaller ear canal and that of an adult.

RITE instruments are suitable for mild to severe hearing losses. As opposed to BTE instruments, the receiver of a RITE hearing instrument is located in the ear canal. This means that the sound does not have to travel through a sound tube, but is delivered directly to the child’s ear canal. This can be advantageous with certain types of high-frequency hearing losses.
Not all children can use RITE instruments – among other things it depends on the size of the ear canal.

This happens when some of the delicate hair cells inside the cochlea get damaged, making them unable to transform the sound vibrations into electrical signals for the brain. A sensorineural hearing loss is permanent.

The Speech Banana is the term used for the marking on the audiogram illustrating on which frequency speech sounds are located at average speech decibel level.

A = Hearing Level in Decibels (dB) and B = Frequency in Hertz (Hz)

Please look under H (Hammer, Anvil and Stirrup).

In the earmould/shell, a small opening or tunnel runs from the faceplate (the side of the ear mould facing out of the ear) to the tip side of the earmould. This opening is called a vent. It can have a number of functions; it ventilates and prevents moisture from building up in the ear canal; the opening allows some sounds to be heard naturally through the ear canal without being processed by the hearing instrument; and it can make the child's own voice sound better.