Since the floor is within 5 feet of the speaker, it is best to have a carpeted floor to absorb floor reflections. A thick, dense carpet and pad will absorb lower frequencies more effectively than a thin one. Due to their complex structure, carpets and pads of natural materials, such as wool and jute, will exhibit a more uniform absorption over the frequency spectrum than synthetic materials will.
It is not necessary to acoustically treat the entire room to achieve good results. Strategic treatment of specific locations can realize considerable benefits. Remember that when sound waves reflect from a flat surface, the angle of reflection is equal to the angle of incidence, just as a mirror reflects light waves. Therefore, the most important location for sound absorbing material is the point where the sound waves reflect to the listener (see Figure 8.2).
Angle X Angle Y
Reflected Sound
DirectSound
Figure 8.2 The sound is reflected at the same angle that it struck the surface; i.e., Angle X = Angle Y. Since light waves obey this same rule, a mirror can be used to find the point which can be acoustically damped to avoid early reflections.
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