Avalon Acoustics Sentinel manual

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 9.2).

Angle X Angle Y

Reflected Sound

Direct Sound

Figure 9.2 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.

Early reflections will tend to diminish the sound stage in the direction of the reflections, i.e. early reflections from the side walls tend to reduce sound-stage width, while early reflections from the back wall will reduce image depth. We have found that a strong sense of depth enhances the feeling of involvement when listening, due to the three-dimensional solidity of images. Therefore, it is more important to have a greater distance from the speakers to the rear wall than to the sides walls. Typically, this is easier to achieve if the speakers are placed along the short wall of the listening room.

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