Audio Engineering

Room Acoustics 855

For orchestral or classical music recording, the studios need to be relatively large and
lively, with reverberation times lying somewhere between 1.2 and 2 s depending on their
size and use. Pop studios tend to be much more damped than this, perhaps typically
varying from 0.4 to 0.7 s.

Broadcast studios would typically have reverberation times as follows:

● Radio talks 0.25 s (60 m^3 )

● Radio drama 0.4 s (400 m^3 )

● Radio music

● Small 0.9 s (600 m^3 )

● Large 2.0 s (1000 m^3 )

● Television 0.7 s (7000 m^3 )

● Control rooms 0.25 s

While it has been recognized for some time now that reverberation time alone is not a
good descriptor of studio acoustics, it is diffi cult to determine any other easily predictable
or measurable parameters that are. Reverberation time therefore continues to be used.

Reverberation time is effectively a measure of the sound absorption within a room or studio,
etc. Its importance therefore really lies within the way it alters with frequency rather than
on its absolute value. It is therefore generally recognized that reverberation time should
be maintained essentially constant within tight limits (e.g., 10%) across the audio band
of interest with a slight rise at the lower bass frequencies generally being permissible. By
maintaining the reverberation time constant, the room/studio is essentially affecting all
frequencies equally—at least on a statistical basis. However, in practice, just because a studio
or control room has a perfectly fl at reverberation time characteristic does not necessarily
guarantee that it will sound all right, but it is a good baseline from which to begin.

Studios are generally designed so that they can either be divided up, for example, by use of
portable screens or by having their acoustic characteristics altered/adjusted using hinged
or fold over panels, for example, with one side being refl ective and the other absorptive
or by the use of adjustable drapes and so on. Isolation booths or voice-over booths are
also frequently incorporated in commercial studios to increase separation. Drama studios
frequently have a live end and a dead end to cater for different dramatic requirements and