ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aAA11. Audibility of individual reflections in a complete sound field. II.

Soren Bech

Bang and Olufsen Ltd., Peter Bangs Vej 15, Struer DK-7600, Denmark

This is a continuation of paper I, presented at the Wallace Clement Sabine Centennial Symposium in Boston 1994. The threshold of detection (TD) and just noticeable difference (jnd) for an increase in level was measured for six individual reflections in a complete sound field. The subjects were instructed to use changes in timbre as the criteria for detection. The sound produced by a single loudspeaker in a normal size listening room was simulated using an electroacoustic setup. The simulated loudspeaker had directivity characteristics according to the measured characteristics of a real loudspeaker and the room surfaces had frequency-dependent absorption characteristics according to measurements. Values of TD and jnd were measured using four subjects for noise and speech. The results confirmed that the first-order floor reflection contributes individually to the timbre of the sound field. The results have further shown that energy in the frequency range 500--2 kHz is important for the TD level. The noise and speech stimuli have been found to result in significantly different TD and jnd values for all reflections, and is contrary to the previous reported results. [Work financed by Eureka project EU105.]