Primer
Crestron
Surround Sound
earliest arriving sound wave is given precedence over the subsequent
reflections and reverberations.
Reverberation and Echoes
The ratio of the direct to reverberant energy is a primary cue for range
and space. Very short delays cause a sound image to shift spatially and
color the tone. Longer delays contribute to a spatial impression of
reverberation. Reverberation can also make speech indistinct by
masking the onset transients.
Sound decreases inversely with the square of the distance. But in an
ordinary room, the sound is reflected and scattered against room
boundaries and objects within the room. Reverberation is essentially an
echo that increases by bouncing off of hard surfaces. Reverberations
are dampened when absorbed by soft materials such as rugs, carpet and
sofas. These reflections are most noticeable when the time delay
between the direct sound and the reverberation gets longer than 30 to
50 ms, the echo threshold.
Reverberations
Acoustic designers place importance on early reflections (arriving
within the first 80 ms), which reinforce the direct sound (as long as the
angle of reflection is not too wide). Reflections arriving after 80 ms add
reverberant energy, which gives the sound spaciousness, warmth and
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Surround Sound
Primer – DOC. 6122
