Page 144 - Master Handbook of Acoustics

FIGURE 6-9 Individual reflections are resolved in these echograms taken at four different positions

3
in a studio of 16,000 ft volume and having a reverberation time of 0.51 sec. The horizontal time
scale is 20 msec/div.

Perception of Sound Reflections

When reproducing recorded sound in a listening room, during the enjoyment of live music in a concert
hall, or in any activity in any acoustical space, the sound falling on the ears of the listener is very
much affected by reflections from the surfaces of the room. Our perception of these reflections is an
important manifestation of sound reflection.

The Effect of Single Reflections

Research studies on the audibility of simulated reflections often use an arrangement of loudspeakers
shown in Fig. 6-10; it is similar to a traditional stereophonic playback configuration. The observer is
seated at the apex so that lines drawn to the two loudspeakers are approximately 60° apart (this angle
varies with the investigator). A monaural signal is fed to both loudspeakers. The signal to one
loudspeaker represents the direct signal. The signal to the other loudspeaker can be delayed by any
amount; it represents a lateral reflection. The two variables under study are the level of the lateral
reflection compared to that of the direct sound, and the time delay of the reflection with respect to the

direct sound.