Page 176 - The Master Handbook Of Acoustics

151
REVERBERATION

dead spaces to realize adequate acoustical separation between tracks.
Music directors and band leaders often require different reverberations
for different instruments, hence hard areas and absorptive areas may be
found in the same studio. The range of reverberation realized in this
manner is limited, but proximity to reflective surfaces does affect local
conditions.
Spaces for speech require shorter reverberation times than for music
because of the general interest in direct sound. In general, long reverber-
ation time tends toward lack of definition and clarity in music and loss
of intelligibility in speech. In dead spaces in which reverberation time is
very short, loudness and tonal balance may suffer. It is not possible to
specify precisely optimum reverberation times for different services, but
Figs. 7-13 through 7-15 show at least a rough indication of recommenda-
tions given by a host of experts in the field who do not always agree with
each other.
The reverberation times for churches in Fig. 7-13 range from highly
reverberant liturgical churches and cathedrals to the shorter ranges of

4

Reverberation time - seconds 3 2 1 Churches

0
0 10,000 100,000 1,000,000
Volume - cubic feet

FIGURE 7-13
“Optimum” reverberation time for churches. The upper area applies to the more rever-
berant liturgical churches and cathedrals, the lower to churches having services more ori-
ented to speech. A compromise between music and speech is required in most churches.