An ongoing auditory research project at the speech and hearing research laboratory of Smith Kettlewell Eye Research Institute is based on the analogy between visual and auditory problems and their solutions.
Animals use both ears to localize sound.
This ability is also important to humans, especially for communication. With two ears we are able to selectively attend to sounds coming from a particular direction while excluding other sounds. This ability is particularly important in noisy surroundings or when several sound sources compete for our attention. We localize sounds by time and intensity information reaching each ear. Sounds from a source at any location other than straight ahead or behind will arrive at the closest ear first and will also be slightly louder in that ear.