Page 180 - The Master Handbook Of Acoustics

155
REVERBERATION

1.0

Upper limit of spread
0.8 Average of 50 living rooms
Reverberation time - seconds 0.6

0.4

0.2 Lower limit of spread

0
100 1,000 10,000
Frequency - Hz

FIGURE 7-17
12
Average reverberation time for 50 living rooms. (After Jackson and Leventhall. )

reverberation time for speech for rooms of this size to be about 0.3 sec-
ond. Only those living rooms near the lower limit approach this, and
in them we would expect to find much heavy carpet and overstuffed
furniture. These reverberation measurements tell us little or nothing
about the possible presence of colorations. The BBC engineers checked
for colorations and reported serious ones in a number of the living
rooms studied.

Artificial Reverberation: The Past

Artificial reverberation is considered a necessity in audio-signal pro-
cessing. Recordings of music played in “dry” (nonreverberant) studios
lack the richness of the room effect contributed by the music hall. The
addition of artificial reverberation to such recordings has become stan-
dard practice, and there is great demand for equipment that will pro-
vide natural-sounding artificial reverberation at a reasonable cost.