Perception of Reproduced Sound: Audibility of Individual Reflections in a Complete Sound Field, II
This paper reports some of the influences of individual reflections on the timbre of reproduced sound. Bech (1995) gave the first report. A single loudspeaker with frequency-dependent directivity characteristics, positioned in a room of normal size with frequency-dependent absorption coefficients of the room surfaces, has been simulated using an electroacoustic setup. The model included the direct sound, 17 individual reflections, and the reverberant field. The threshold of detection and just-noticeable differences for an increase in level were measured for individual reflections using four subjects for noise and three for speech. The results have confirmed the findings of Bech (1995) that the first-order floor reflection is likely to individually contribute to the timbre of reproduced noise. However, for a speech signal none of the investigated reflections will contribute individually to the timbre. The threshold of detection is suggested to be determined by the spectral changes in a dominant frequency range of 500 Hz-2 kHz. An increase in the level of individual reflections is most likely to be audible for the first-order floor reflection for speech and noise. For a noise signal, additional reflections from the wall to the left and behind the listener also belong to this group.
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