Conversely, improper placement of the loudspeakers can result in uneven frequency response. This results in diminished bass quality. Please refer to Figure 8.6.
Figure 8.6 - Uneven frequency response caused by improper placement of the speakers. In this case, the speaker is 2.0 feet from both the side and rear walls.
As frequency increases and wavelength becomes more similar to the distance to the boundary, the phase difference between original and reflected waves increases, and the air coupling effect is diminished. In particular, when the wavelength equals about four times the distance to the boundary, the reflected wave is antiphase to the original wave, resulting in a cancellation (dip) in the output. At frequencies above this level, the effect becomes less significant and creates similar but smaller variations in output. Figures 8.7 and 8.8 illustrate these concepts.
Figure 8.7 -
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