Sensation of Sound Intensity and Perception of Loudness

Abstract

This chapter is on sensation of sound intensity and perception of loudness. Since some of the relevant matter (on scaling concepts of loudness) has been presented in Chap. 30, and because a considerable portion of research on loudness is done outside musical contexts (namely, in industrial and environmental noise control as well as in audiology), this chapter condenses facts and models more than the previous two on pitch and timbre respectively. Section 33.1 of this chapter offers the physical and physiological basis of sound intensity sensation while Sect. 33.2 discusses features of some models of loudness sensation that have been established in psychoacoustics over the past decades. Since these models were originally designed for stationary sound signals and levels, and have been tested mostly in lab situations, they cannot adequately cover a range of real-world sound types found in natural or technical environments. In music genres such as techno presented in discos, or heavy metal performed in live music venues or at open air festivals to audiences at very high sound pressure levels, sound is heavily processed in regard to dynamics and spectral energy, which calls for appropriate measurement and assessment of sensory effects. Different from perception of pitch (where samples of subjects respond more or less in similar ways to certain types of sound signals), perception of loudness shows a high degree of variability even within groups of musically trained subjects reflecting their musical background and preferences (Sect. 33.3). Recent empirical evidence demonstrates that subjects judge loudness for various musical genres on a category scale (from very soft to very loud), however, the center (relative to loudness level and loudness scales) and the range of each category differ considerably, for individual subjects.