User Manual

Speaker System Design Guide for
Yamaha Sound System Simulator
phase interference are indicated between speakers because the wavelengths of
the frequencies in question are relatively long compared to the distance between
the speakers. However, areas of phase interference do appear in the measured
results on the right side of each figure. These areas are most likely formed through
interference between direct sound from the speakers and initial reflections from the
walls. The wide and even areas of phase interference between direct and initial
reflected sounds indicated in the low frequency bands are caused by two factors.
One factor is the large amount of sound reflected from the walls caused by the
wide directivity of the speakers. The other factor is that because the variations in
the wall surface are small compared with the wavelengths in the low frequency
band, there is no diffusion effect. The influence of reflected sound may manifest
itself as unevenness in sound pressure distribution levels. This can also be
interpreted as the influence of the venue type. For typical enclosed speakers,
directivity is difficult to control in the low frequency bands, so you cannot change
the phase interference in the low frequency bands by changing the speaker angles.
It is important to understand that this type of interference will not appear in speaker
arrangement evaluations that only take direct sound into account, but that it will
appear in the actual sound field.
125 Hz 250 Hz
Figure 4: Sound pressure distributions by frequency band (low frequency bands)
(left diagram: the results of Y-S
3
, right diagram: measured results)
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