mix bag

Question 1

Why are low frequency bone conduction thresholds enhanced by occlusion of the ear canal? (6marks)

Answer 1

Since bone conduction vibrates the skull
this in turn creates vibrations in the ear canal wall, producing sound waves within the ear canal space.
Those sounds are ‘trapped’/’housed’ in the ear canal due to the headphones/earphones blocking the exit path.
As opposed to those sounds typically leaking out of the ear canal (if unoccluded), occluding with HPs/IPs causes the sound waves to travel to the cochlea via air conduction, increasing the energy the cochlea is receiving, thus improving the BC responses.
At 250Hz the BC thresholds can be improved by up to 30dB; 500Hz by 20dB and at 1kHz by 10dB.
However, these responses are not true thresholds (i.e. not representative of the cochlea sensitivity).