History [of auditory perception]
The notion of musical notes and of concepts such as octaves goes back at least five thousand years. Around 550 BC the Pythagoreans identified various potential connections between numbers and the perception of sounds. And over the course of time a wide range of mathematical and aesthetic principles were suggested. But it was not until the 1800s, particularly with the work of Hermann Helmholtz, that the physical basis for the perception of sound began to be seriously investigated. Work on speech sounds by Alexander Graham Bell and others was related to the development of the telephone in the late 1800s. In the past few decades, with better experiments, particularly on the emission of sound by the ear, and with ideas and analysis from electrical engineers and physicists the basic behavior of at least the cochlea is becoming largely understood.