ABSTRACT
Chapter 2 Audio Surveillance describes information that is gathered through sound technologies within human hearing ranges, such as phone taps, listening devices, tape recorders, and amplifiers. Chapter 3 focuses on infrasound and ultrasound, frequencies below and above human hearing ranges. This chapter focuses primarily on acoustic-sensing and sonar devices that are designed for underwater detection, ranging, and imaging applications, many of which utilize frequencies outside of human hearing range.
