Hearing and Hearing Loss Degrees of hearing loss

Sound is measured according to loudness and pitch or frequency. The loudness of a sound is measure in decibels (dB) and pitch or frequency is measured in hertz (Hz).

The degree of hearing loss is displayed on an audiogram – a chart which records a person's hearing thresholds – the softest sounds they can hear.

Children with normal hearing can usually hear sounds quieter than 20dB. When hearing thresholds are outside the normal range, they are considered to have one of the four degrees of hearing loss:

Mild hearing loss (cannot hear sounds softer than 21-40dB): Children will have difficulty hearing soft speech and conversations, but can usually hear if there is no background noise and the voice is clear. Other soft sounds such as a bird chirping or a dripping tap may not be heard.

Moderate hearing loss (cannot hear sounds softer than 41-60dB): Children will have great difficulty hearing normal conversations.

Severe hearing loss (cannot hear sounds softer than 61-90dB): Children will not hear normal conversation, but will usually respond to a loud sound such as a door slam. Other louder sounds such as a phone ringing or a dog barking may not be heard.

Profound hearing loss (cannot hear sounds softer than 91db): Children will not hear most sounds (including speech). Very loud sounds such as an aeroplane flying above or a lawnmower may not be heard.

See the Related Links on the left of the screen for more on measuring degrees of hearing loss.