Localisation

Balanced hearing is imperative for our ability to hear where a sound is coming from, it can be a source of embarrassment i.e. where is the sound coming from when someone speaks, or potential danger i.e. 'which direction is that motorbike coming from' when crossing a road. Our brain instinctively locates a sound source by measuring tiny differences in duration and intensity between each ear. When these minute differences are perceived by the brain it enables us to locate the sound source. This allows the ears to provide 360 degrees of perception, something unique to our auditory sense. Using one hearing aid when two are needed reduces the ability of the brain to localise sound as the diagram below illustrates.