Sound and signals in music technology and digital audio
As shown in Figure 2.1, an acoustic signal, such as the sound produced by a drum, travels as pressure waves through the air. When the drum is struck by a player, the vibrations produced in the skin of the drum head alternately compress and rarefy the air immediately surrounding the drum. These pressure waves travel through space, rather like ripples on the surface of a pond. When these waves fall on our ear, they cause vibrations to be set up in a membrane located at the boundary of the outer and middle ear and these vibrations are perceived as sound by the auditory system. However, as also shown in Figure 2.1, it is possible to transmit these acoustic signals via an electrical system.