Hearing loss explained
Hearing tests measure what sounds you can and can’t hear, and there are a variety of tests that an audiologist can use to find out what your hearing is like and where the problem may be if there is one.
Usually your hearing test results will be plotted on something called an audiogram (see an example of a blank audiogram graph below). This graph shows how loud you need a variety of sounds to be before you can just hear them—your hearing thresholds.
For example, people with normal hearing can hear different pitch sounds down as low as 20 decibels (dB) or less. These sounds are very quiet. Someone who cannot hear sounds until they are very, very loud, about 100 dB for example, will hear very little in the everyday world, except maybe a jet taking off or an explosion.
Characteristics of hearing impairment
It’s a common belief that hearing impaired people just can’t hear sounds loudly enough, but the problem is a lot more complicated than that. There are 4 main problems caused by hearing loss.
- Soft sounds can’t be heard, such as some speech sounds like ‘s’ and ‘p’ and ‘ch’.
- Key parts of particular speech sounds may not be audible, meaning sounds are misheard and words misunderstood.
- Sounds are difficult to separate, so voices can become jumbled up with background noise.
- There is a reduced range of hearing in the impaired ear, meaning that soft sounds can’t be heard but loud sounds may actually be intolerable.
How is hearing loss described?
Hearing loss is measured in decibels, but is usually described in terms of degree of impairment for hearing conversational speech.
Sometimes people give their hearing loss as a percentage, for example, ‘I have a 50 per cent loss of hearing’. This may seem easier to understand, but it is not really the best way to describe hearing. A 100 dB hearing loss is a considerable impairment, but it certainly does not mean total deafness.
Percentages are only used by audiologists for purposes of compensation when describing a hearing loss caused by a noisy work place or accident. In these cases, a percentage ‘disability’ is estimated to determine how much compensation a person may be due.
What do the different degrees of hearing loss mean in ‘real life’ terms?
The following classifications show the approximate relationship between the decibel hearing loss and the degree of difficulty it may cause.
0–20 dB: Range of normal hearing
If hearing thresholds fall within this range, hearing is said to be within normal limits.
21–45 dB: Mild hearing loss
A person with a mild loss would have some difficulty hearing soft speech and conversations, but can often manage in quiet with clear voices. Voices will often sound muffled and unclear. Speech and language usually develop normally if a child is fitted with hearing aids early. Hearing aids will assist most hearing problems.
46–60 dB: Moderate hearing loss
A person with this degree of loss would have difficulty understanding conversational speech, particularly in the presence of background noise. TV and radio would have to be turned up to be heard. Speech and language development are generally affected if a hearing aid is not provided early to a child born with this degree of loss. Hearing aids usually assist most hearing difficulties if speech discrimination (that is, how clearly speech is heard) is good and the listening environment is not too noisy.
61–75 dB: Moderately severe hearing loss
Without a hearing aid, only a raised voice at a close distance can be understood by people with a moderately severe hearing loss. Without amplification, a child’s speech and language would generally not develop spontaneously and speech quality would be poor. However, hearing aids should allow conversational speech to be heard in quiet listening conditions, and with appropriate training most speech sounds should be correctly recognised and reflected in a child’s own speech. Visual cues are a definite advantage. Voices may sound quite distorted, even when loud enough, and this can restrict the benefit of hearing aids.
76–90 dB: Severe hearing loss
For severely hearing impaired people, normal conversational speech cannot be heard. Speech and language do not develop spontaneously in a child born with this degree of impairment. Hearing aids will amplify many speech sounds and will greatly assist a child to develop speech, but speech quality is likely to be affected. Visual cues will usually assist in understanding speech.
91+ dB: Profound hearing loss
Profoundly deaf people have similar difficulties as people with a severe hearing loss but there is greater inconsistency in the benefit from hearing aids (particularly with 105+ dB hearing losses). Learning to speak is difficult for children born with a profound hearing loss, but it depends on the degree of the loss as to how difficult it will be. Some profoundly deaf people can understand clear speech via listening alone in good auditory conditions with a hearing aid, while others find it impossible.
Hearing aids can make a big difference
Ask your audiologist to explain your audiogram. And remember that hearing aid technology has come a long way and that very few people with hearing loss cannot benefit considerably from a modern, well-fitted hearing aid.
But there are also special ideas and easy techniques that can help you use your hearing as well as possible. Discuss any questions or concerns you have with your audiologist.
Last Reviewed: 17 August 2005
Sponsored links
Related Topics
A-Z of ear health and hearing
Support Group Searches
Health support groups for Deafness and hearing impairmentHealth support groups for Hearing impairment
Related Links
Australian Hearing Advertisement
Advertisement
Advertisement
