Handbook for Sound Engineers

164 Chapter 7

Classical concert halls serve first of all for music
events ranging from soloist presentations to the great
symphony concert with or without choir. They are
mostly equipped with a pipe organ and their
room-acoustical parameters must satisfy the highest
quality demands. Electroacoustical systems are used for
vocal information and for mutual listening with special
compositions, but are generally still ruled out for influ-
encing the overall room-acoustical parameters.

General concert halls can be used for numerous music
performances, among others for popular or pop
concerts. Here it is the use of an electroacoustical sound
reinforcement system that overrides the room-acoustical
parameters of the hall. In accordance with the variety of
events to be covered by these halls, they should be
tuned to a frequency-independent reverberation time of
the order of 1.2 s and feature high clarity.

Sports halls, gymnasiums have to provide an acous-
tical support for the mutual emotional experience. This
concerns, first of all, the supporting acoustic correspon-
dence of the spectators between themselves and the
performers. Thus there are only few sound absorbing
materials to be used in the spectators’ areas and sound
reflecting elements to be provided towards the playing
field. The ceiling of the playing field should be more
heavily damped so as to enable it to be used also for
music events, in which case an electroacoustical sound
reinforcement system is to be used. The same applies to
open and partially or fully covered stadiums where
sound absorption above the playing field is a natural
feature with the open ones.

Show theaters are generally used only on negligibly
few occasions with natural acoustics, an exception
being “Singspiel” theaters with an orchestra pit.
Predominantly, however, an electroacoustical sound
reinforcement system is used for the functions of
play-in and mutual hearing as well as half or full play-
back. The room-acoustical parameters of the theater
room have, with this form of utilization to comply with,
the electroacoustical requirements. The reverberation
time should therefore not exceed a frequency-indepen-
dent value of 1.4 s and the sound field should have a
high diffusivity so that the electroacoustically gener-
ated sound pattern does not get distorted by the acous-
tics of the room.

Rooms with variable acoustics controlled by mechan-
ical means show some positive result only in a certain
frequency range, if corresponding geometric modifica-
tions of the room become simultaneously visible. The

room-acoustical parameters have always to coincide

with the listening experience that means they must also

be perceived in a room-size and room-shape-related

manner. Experimental rooms and effect realization (e.g.,

in a virtual stage setting of a show theater) are, of

course, excluded from this mode of consideration. In

theater rooms and multipurpose halls it is possible to

vary the reverberation time by mechanical means within

a range of about 0.5 s without detrimental effect on

spatial impression and timbre. At any rate one should

abstain from continuously variable acoustic parameters,

house superintendent acoustics, since possible interme-

diate steps could lead to uncontrolled and undesirable

acoustic settings.

Sacral rooms. Here we have to distinguish between

classical church rooms and contemporary modern sacral

buildings. With the classical rooms it is their size and

importance that determine their room-acoustical param-

eters—e.g., a long reverberation time and an extreme

spaciousness. Short reverberation times sound inade-

quate in such an environment. The resulting deficiency

in definition, inconvenient—e.g., during the sermon—

has to be compensated by providing additional initial

reflections through architecturally configured reflec-

tors, or nowadays, mostly through an electroacoustical

sound system. With music presentations one has, in

various frequency domains, to adapt the style of playing

to the long decay time (cf. Baroque and Romanesque

churches). Electroacoustical means can serve here only

for providing loudness.

From the acoustical point of view, modern church

buildings acquire to an increasing degree the character

of multipurpose halls. Thanks to appropriately adapted

acoustics and the use of sound reinforcement systems

they are not only adequate for holding religious

services, but can also be used as venues for concerts and

conferences in good quality.

7.3.2 Structuring the Room Acoustic Planning

Work

7.3.2.1 General Structure

The aim of room-acoustical planning consists of safe-

guarding the acoustical functionality under the envis-

aged utilization concepts of the auditorium for the

performers as well as for the audience. With new build-

ings such details should be considered in the planning

phase, whereas with already existing rooms an appro-

priate debugging should be an essential part of the