User Manual

Speaker System Design Guide for

Yamaha Sound System Simulator

2. Evaluating the Response at Specific Points

The effects of interference between multiple speakers are manifested in the response at a

specific point through dips in frequency characteristics. In the actual sound field, it is

expected that the depth of the dips will be reduced by reflected sound.

As in the previous section, this section compares the results of direct sound computations to

those of actual measurement results in the case when a two-speaker array is placed in the

center position of a hall.

; Frequency Characteristics at a Specific Listening Point

¾ Evaluating Sharp Dips

Figure 5 shows the computed and measured results at point A (x = 6 m, y = 6 m).

Point A is 6 m to the left of the center of the seating area (approximately in the

middle of the left side of the seating area). The blue line represents the Y-S

computed results. The red line represents the measured results in the actual hall. It

shows the values integrated over 15 ms after the reception of direct sound. The

pink line also represents the measured results in the actual hall, but it shows the

values integrated over 100 ms after the reception of direct sound. The spectrum of

the measured results was acquired through an 8192-point Fourier transform and

then converted into 25-point moving averages. The vertical axis of the graph

represents relative sound pressure levels, and the maximum value for each line is

set to 0 dB.

In the Y-S

computed results (the blue line), a dip of approximately 20 dB occurs at

approximately 1.2 kHz. It is difficult to determine the significance of this dip, but

Y-S

has an auralization feature that simulates the audio response so that you can

evaluate it.

One must be aware that in actual sound fields, these kinds of dips are mitigated by

the effects of reflected sound. In the values integrated over 15 ms (the red line), the

dip appears in a relatively high frequency range, but it is mitigated to within 10 dB

even at its deepest point. This dip also appears in the values integrated over 15 ms

and in the values integrated over 100 ms, indicating that the frequency response of

the strong direct sound that arrives from the speakers has a strong influence on the

overall frequency response of the initial reflected sound, and thus also has a strong

influence on the listening experience. This further underscores the importance of

checking the effects of interference between speakers at the design stage.