Timothy C. Hain, MD Page last modified: February 24, 2018
People with hearing loss, or even with "normal" audiograms, often compain of greater difficulty in understanding speech, when there are competing sounds sources such as other people talking in a restaurant or party, or loud music.
There are several reasons for this --
Pienkowski has discussed the problem of having problems even when the audiogram is normal -- problems with the input, with the brainstem processing, with cortical processing among others (Pienkowski, 2017). We ourselves think the main cause is wear/tear on the cochlea (i.e. input system) that is just not detected by the relatively crude audiogram test.
The cocktail party effect denotes the advantage that a listener gains from having two ears separated in space when separating a signal from auditory noise.
In humans, when the speaker and noise come from different locations, there can be an improvement of up to 18 dB. (Gatehouse, 1987; Saberi et al, 1991).