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10.6.16 Testing for Hearing Loss
There are set international standards used to quantify loss of hearing, called ISO (International Standards Organisation) standards. These have been adopted by the Australian Hearing Service (AHS) for use in Australia. Standard levels approximate the intensity of the faintest sound that can normally be heard.
These levels have been determined based on the hearing of young people who are considered to have normal hearing and no ear disorders. Threshold values are obtained at each frequency for these people and are then averaged out. The average values then become values for 'normal' hearing.
A person's hearing level is the difference in decibels between the faintest pure tone that can be heard and the normal level given by the standard.
The values 9 to 20 dB are considered to be normal hearing range.
Hearing loss examples:
1.Someone who can't hear a sound until it is presented at 40 dB for each frequency will be aware of a hearing problem. He or she will have difficulty listening to the radio or television without an increase in volume.
2.If sound is just heard at 70 dB, the person will be unable to hear enough of speech to recognise what is being said. He or she would be considered to be deaf for speech.