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'A' Level Medical Option Questions - The Ear

Q11.

(a) Define the threshold of hearing, I0

The threshold of hearing is the minimum intensity (at which a note of 1.0 kHz ) can be detected by a normal ear.

(2 marks)

(b) A hearing test was used to obtain threshold hearing audiograms for several people. The audiogram shown below was obtained for a person with normal hearing.

On the audiogram:

(i) sketch a curve, labelled A, for a person suffering hearing loss due to old age

Increased loss with increased frequency

- just above the 'normal' trace for lower frequencies (indicating some loss) then well above the curve for higher frequencies (indicating more loss at higher frequencies).

(1 mark)

(ii) sketch a curve, labelled B, for a person suffering hearing loss due to excessive noise

Slight loss at all frequencies but a marked 'notch' of severe loss at 4 kHz.

- just above the 'normal' trace for all frequencies (indicating some loss) then climbing well above the curve for the region around 4 kHz - returning to being just above the normal trace for much higher frequencies.

(2 marks)

(Total 5 marks)