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Preferred delay time of a single reflection
In an anechoic room the direct sound was radiated from the loudspeaker in front of the listener and the single reflection were radiated from the loudspeaker of the listener's lateral side. The delay time of the single reflection was varied from 8 to 256 ms. The amplitude of the direct sound and the reflection were the same (Fig. 1). Figure 2 shows the preference score obtained from 13 subjects. The preferred delay time for the music motivs A and B greatly differs and were 130 and 35 ms, respectively.
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Fig. 1. Direct sound and single reflection
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Fig. 2. Delay time of the single reflection and preference.
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| Music motif A |
Music motif B |
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| Delay time （ms） |
8 | ||
| 16 | |||
| 32 | |||
| 64 | |||
| 128 | |||
| 256 | |||
We hear the "echo (disturbance)" when the delay time of the reflection is much longer than the preferred one. When the delay time is very short, we perceive the colorlation due to the interference between the direct sound and the reflection. We may hear the echo for the 256 ms delay time for music motif A, and the echo may be perceived for more than 64 ms of the delay time for the motif B. The music signal which has a shorter te is more sensitive to the change of the delay time of the reflection.
