Random Sound Fields in Rooms: Fid-Bau Portal

Random Sound Fields in Rooms

Tohyama, Mikio

Responses excited by random noise may exhibit a trend of frequency characteristics of sound paths. This chapter deals with temporal-spatial distributions of reverberation according to the linear system theory. Random sound field may not be uniform, because in-phase summation is possible between direct and reflection or scattered waves on the boundary. Reverberation decay curves are written by a superposition for $3 -$ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$3-$$\end{document}, $2 -$ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2-$$\end{document}, and 1-dimensional fields. The formulation is a hybrid of the wave-theoretic and geometric-acoustical approaches such as the modal density and mean-free-paths. Thus, inherent frequency characteristics in room shape might be well presented by the hybrid formulation. Phase differences in reverberation between a pair of spatial points would be a basis for binaural hearing such as subjective diffuseness or sound image perception. This chapter may imply a function theoretic approach to binaural sound fields, where cepstral analysis may be the key to a bridge between the phase and energetic sound nature. Spatial or inter-aural correlations in random sound field follows a sinc function of the equivalent distance between a pair of receiving positions. The correlation functions imply binaural sound fields constructed by inter-aural level difference with a time delay.