Avalon Acoustics Sentinel - Manual (Page 49)

49
10.4 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. When the wavelength of the sound is large compared to the
distance to the boundary, 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.