One way to look at hearing is to think about loudness. A person with normal hearing will hear very quiet sounds, prefer sounds at a medium level, and will be able to tolerate very loud sounds.

Sounds can also be described as high-toned or low-toned. The sounds of a violin or a bird singing are examples of high-toned sounds - whereas a bass or some male voices are examples of low-toned sounds.

Hearing is both measured in terms of loudness (intensity) and pitch (frequency). The unit of measurement for intensity is Decibel Sound Pressure Level (dBSPL). For pitch the unit of measurement is Hertz (Hz). A person with normal hearing can typically hear sounds up to 120 dBSPL. Above 120 dBSPL sounds become very uncomfortable and can be damaging. The same person can typically hear and tolerate sounds within the pitch range of 20 to 20,000 Hz. However, during a hearing test only the range from 125 to 8000 Hz is measured. The speech sounds are included in this range.

If you want to know what sounds your child can hear, an audiologist can help you by doing a hearing test.

A hearing test shows the level at which your child can or cannot hear different tones. There are several other types of measurement methods:

• Otoacoustic emissions (OAE), for newborns and infants. OAE are very weak sounds from the cochlea when audible sounds stimulate the cochlea. Children with normal hearing produce emissions – those with hearing loss greater than 25-30 dB don’t.
• Auditory brainstem response (ABR), for newborns and infants. Electrodes are placed on the head of the child, and brain wave activity in response to sound is recorded.
• Visual reinforcement audiometry (VRA), for children between 6 months and 2 years of age. The child is trained to look towards a sound source and is ‘rewarded’ through a visual reinforcement such as a moving toy.
• Conditioned play audiometry (CPA), for children between the age of 2 and 3 years. The child is trained to perform an activity each time a sound is heard.
• Conventional audiometry where the child raises the hand when hearing a sound; this technique can be used for older children.

These are just examples of the different methods of testing available. Your child's age and ability to cooperate will determine which methods the audiologist will choose to use. Performing a hearing test, especially on smaller children, can take some time. Often more tests are required in order to define the degree of hearing loss.