Physics can tell us the mechanism by which disturbances propagate through the air. If this is our definition of sound, we have the problem that in physics there are no limits to the frequencies and levels which must be considered. Biology can tell that the ear only responds to a certain range of frequencies provided a threshold level is exceeded. This is a better definition of sound; reproduction is easier because it is only necessary to reproduce that range of levels and frequencies which the ear can detect.
Psychoacoustics can describe how our hearing has finite resolution in time, frequency and spatial domains such that what we perceive is an inexact impression. Some aspects of the original disturbance ...