Avalon Acoustics OPUS Ceramique Loudspeaker manual Bass reinforcement

8.4 Bass reinforcement

By bass reinforcement, we mean the effect of the room boundaries on the propagation of sound. It is widely known that speaker placement relative to the floor and walls can affect the relative amount of bass that the system produces.

To make this interaction more clear, let us refer to the optical analogy of the candle. Similar to the way that the mirror reflected the light of the candle, so can the surfaces near the loudspeaker reflect the sound waves back into the listening room. However, when the path length difference of the reflected wave is short relative to the wavelength of the sound, the reflected wave is substantially in-phase with the original wave. When this condition is met, the coupling coefficient between the speaker diaphragm and the air increases, and the speaker efficiency increases. This changes the actual frequency response of the speaker, and is not attributable to standing waves or other room resonances.

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