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'A' Level Medical Option Questions - The Ear

Q13. Three people are given routine hearing tests. The graphs below show the threshold hearing level of the patients at different frequencies. Graph A is for the patient with normal hearing.

(a) State and explain one reason why the dBA scale is used.

The dBA scale gives a vitually flat response across the whole frequency range of human hearing as it has been adjusted to take in the frequency response of the human ear. Frequencies where sounds would be detected by the human ear as quieter than a sound at 1000 Hz have the signal boosted to that loudness and those that would be detected by the human ear as louder than a sound at 1000 Hz have had the volume of the loudness reduced. The variation with which we detect sounds of the same intensity across the spectrum of hearing has been compensated for.

(2 marks)

(b) Describe the significant difference between graph A and graph B, and suggest a possible cause.

Loss in hearing increases as frequency increases, this type of loss is due to old age

For the mark you have to both describe how the graph shape has changed and explain it.

(1 mark)

(c) Describe the significant difference between graph A and graph C, and suggest a possible cause.

The loss in hearing increases up to 4 kHz and then decreases after this. There is a maximum loss at 4 kHz. This type of loss is because the person has been subjected to excessive noise - loud sounds.

For the mark you have to both describe how the graph shape has changed and explain it.

(1 mark)

(Total 4 marks)