On time-varying loudness and nonlinearly propagated sound

Abstract

Time varying loudness models have been found to be highly correlated with subject judgments for many sources of noise. Among these sources are impulsive sounds such as sonic booms, blast noise, and thunder. Aside from the short temporal duration, all of these sound sources are distinctive in that each is of high enough amplitude to have nonlinear propagation effects occur, which change the temporal and spectral character of a signal over distance. Because of this, it is possible that differences in how a model handles spectral content may result in differences in loudness predictions over distance. A series of simulated nonlinear sources were propagated and its time-varying loudness calculated from both the Moore & Glasberg and Zwicker model. These predictions will be compared to examine how these models differ when the spectral content of the signal changes. Other parameters, including historical level metrics and those derived from loudness time histories, such as the loudness time derivative, will also be discussed.