The Audiogram (& Audiometry)

An audiogram is a graph illustrating the amount of hearing loss that an individual has in each ear. Along the horizontal, the numbers from 125 to 8000 are the frequencies, or different pitches of sound. Frequency is expressed in cycles per second, or Hertz. The higher the frequency, the higher the pitch of the sound, i.e. blue tits’ song is around 6000Hz.  Loudness (shown on a scale on the vertical) is measured in decibels. 

Conversational speech is around 65 dB, and a jet engine taking off very near you is about 120 dB. During the hearing test, the audiologist presents a single frequency at a time. The softest tone at which a person can hear that frequency is marked on the audiogram at that intensity. This is called the “hearing threshold” of that frequency.

Your audiogram is a “picture” of your hearing. It indicates how much your hearing varies from normal and, if there is a hearing loss, where the problem might be located. There are different types and degrees of hearing loss. Depending on the part of the ear that is affected, experts generally distinguish between four main types of hearing loss: conductive, sensori-neural hearing loss, mixed and neural hearing loss.

Picture 1:
NORMAL HEARING
Scores between -10 and 25dB are considered ‘normal’
   Fig. 2                           Fig. 3                           Fig. 4                           Fig.5     
2. TYPICAL HEARING LOSS IN AN ADULT
Where the majority of the scores are between 20 and 40, the loss will be described as MILD. Between 40 and 70, as MODERATE. So this chart shows a typical age-related MILD TO MODERATE hearing loss for a person in their 70s. Hearing aids tend to work very well in addressing this type of loss.
3. TYPICAL NOISE INDUCED HEARING LOSS IN AN ADULT
Where the low frequency scores (those below 1000Hz) are mostly normal or ‘mild’ , followed by a sharp drop into the high frequencies, and usually a little correction at 6 or 8000Hz. In this case, this is a MILD HIGH FREQUENCY HEARING LOSS. Hearing aids will usually help with this loss.
4. PRECIPITOUS NOISE-INDUCED HEARING LOSS IN AN ADULT
Where the low frequency scores (those below 1000Hz) are mostly normal or ‘mild’ , followed by a very sharp drop into the high frequencies. This type of loss is usually caused by long-term exposure to explosive type sounds. RIC aids are best for this loss. 
5. An example of a COOKIE BITE LOSS –
where the graph dips / recovers at one or more points. Often indicating a more 
complex set of causes. This patient may need more fine-tuning appointments.
   Fig. 6                            Fig. 7                           Fig. 8                           Fig. 9
Fig. 6
One sided hearing loss. This type could be addressed with a CROS system.
Fig. 7
A total loss of hearing in one ear, and an aidable hearing loss in the other ear. This could be addressed with a BiCROS system. 
Fig. 8
This shows a profound hearing loss in the left ear and a mild hearing loss in
the right ear. Historically, this loss was often treated with one aid for the worst ear. Now, normally 2 are recommended.
Fig. 9
An example of a REVERSE SLOPE LOSS. Sometimes seen in those with Meniere’s disease. This patient may need more fine-tuning appointments.
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