Audio and Electroacoustics

Abstract

This chapter surveys devices and systems associated with audio and electroacoustics: the acquisition, transmission, storage, and reproduction of audio. The chapter provides an historical overview of the field since before the days of Edison and Bell to the present day, and analyzes performance of audio transducers, components and systems from basic psychoacoustic principles, to arrive at an assessment of the perceptual performance of such elements and an indication of possible directions for future progress. The first, introductory section is an overall historical review of audio reproduction and spatial audio to establish the context of events. The next section surveys relevant psychoacoustic principles, including performance related to frequency response, amplitude, timing, and spatial acuity. Section 3 examines common audio specifications, with reference to the psychoacoustic limitations discussed in Sect. 2. The specifications include frequency and phase response, distortion, noise, dynamic range and speed accuracy. Section 4 examines some of the common audio components in light of the psychoacoustics and specifications established in the preceding sections. The components in question include microphones, loudspeakers, record players, amplifiers, magnetic recorders, radio, and optical media. Section 5 is concerned with digital audio, including the basics of sampling, digital signal processing, and audio coding. Section 6 is devoted to an examination of complete audio systems and their ability to reproduce an arbitrary acoustic environment. The specific systems include monaural, stereo, binaural, Ambisonics, and 5.1-channel surround sound. The final section provides an overall appraisal of the current state of audio and electroacoustics, and speculates on possible future directions for research and development.