Directional Exploration of Two Reverberant Sound Fields

Abstract

The reverberant sound fields of two comparably sized but acoustically dissimilar halls (recital hall and theatre) were excited by means of a steady-state random noise source, located on stage. Using a specially constructed directional microphone with known directivity, octave-band sound-pressure measurements were made near the center of each audience area. A total of nine directions, covering the hemisphere of exposure to the sound field, were explored in each hall. It is shown that the loudness disparity between the two halls, which stands in good agreement with the measured reverberation times, is attributable to nonfrontal sound only. Typically, the level of nonfrontal sound in the theatre was found to be 4 dB below the level of nonfrontal sound in the recital hall, while frontal sound levels in the two halls were essentially equal. The measurement data are discussed with reference to subjective impressions of acoustical “envelopment.”