Humans expend the time delay between the arrival of a sound wave at each ear to discern the direction of the source. In frogs,lizards and birds the distance between the ears is too small. However, they have a cavity connecting the eardrums, and in which internal and external sound waves are superimposed. Using a universal mathematical model,researchers at the Technical University of Munich (TUM) have now for the first time shown how modern signals are created in this "inner ear" used by animals for localizing sounds.
Source: phys.org