Introduction

Abstract

Sounds are physical waves that propagate in the air or other media. Such waves, whichmay be expressed as changes in air pressure,may be transformed by an analog audio system using a transducer, such as a microphone, into continuous electrical waves in the forms of current and/or voltage changes. This transformation of sounds into an electrical representation, which we call an audio signal, facilitates the storage, transmission, duplication, amplification, and other processing of sounds. To reproduce the sounds, the electrical representation, or audio signal, is converted back into physical waves via loudspeakers.