Handbook for Sound Engineers

Acoustics for Auditoriums and Concert Halls 163

measures can be characterized as follows:

Auditoriums, congress centers are mainly used for
speech presentation. They are mostly equipped with a
sound reinforcement system, but may sometimes also
do without it. Music performances without sound rein-
forcement systems take place in a reduced style as a
setting for ceremonial acts and festivities. Owing to the
short reverberation time abiding their utilization
concept, larger concert performances mostly require in
such rooms the room-acoustical support of electro-
acoustical equipment (see Section 36.1).

Spoken-drama theaters serve in their classical form
for speech presentation with occasional accompani-
ment by natural music instruments and vocalists. Apart
from serving as a support for solo instruments in a
music performance, utilization of electroacoustical
systems is reserved almost exclusively for playing-in
effects or for mutual hearing.

Multigenre theaters are gaining in the theater scene an
ever-growing importance against the pure music or
spoken-drama theater. The presentation of speech or
music from natural sources must be possible here
without compromise. While the classical music or
spoken-drama theater got along with an average rever-
beration time of about 1 s, the trend in the planning of
modern multigenre theaters tends to a somewhat longer
reverberation time of up to 1.7 s with a strong portion of
definition-enhancing initial sound energy and a reduced
reverberance measure (less energy at the listener seat
after 50 ms than within the first 50 ms). Here it may
also be appropriate to make use of variable acoustics for
reverberation time reduction, if, for example, electro-

acoustical performances (shows, pop concerts, etc.) are

presented. This reverberation time reduction should be

obtained by shortening the travel paths of the sound

reflections rather than by sound absorption measures

which tend to reduce loudness. The separation of room

volumes (e.g., seats on the upper circle, reverberation

chambers) leads mostly to undesirable timbre changes,

unless these volumes are carefully dimensioned.

Electroacoustical systems have in multigenre

theaters mostly mutual hearing and playing-in func-

tions. Concert presentations on the stage with natural

sound sources require the additional installation of a

concert enclosure.

Opera houses having a large classical theater hall must

be capable of transmitting speech and music presenta-

tions of natural sources in excellent acoustic quality

without taking recourse to sound reinforcement. Speech

is mainly delivered by singing. In room-acoustical plan-

ning of modern opera houses the parameters are there-

fore chosen so as to be more in line with musical

requirements (longer average reverberation time of up

to 1.8 s, greater spaciousness, spatial and acoustical

integration of the orchestra pit in the auditorium). Elec-

troacoustical means are used for reproducing all kinds

of effects signals and for playing-in functions (e.g.,

remote choir or remote orchestra). This implies that the

sound reinforcement system is becoming more and

more an artistic instrument of the production director.

Concert presentations on the stage with natural

sound sources also require the additional installation of

a concert enclosure which has to form a unity with the

auditorium as regards proper sound mixing and

irradiation.

Multipurpose halls cover the widest utilization scope

ranging from sports events to concerts. This implies that

variable natural acoustics are not efficient as a planning

concept, since the expenditure for structural elements

generally exceeds the achievable benefit. Parting from a

room-acoustical compromise solution tuned to the main

intended use, with a somewhat shorter reverberation

time and consequently high definition and clarity,

appropriately built-in structural elements (enclosures)

have to provide for the proper sound mixing required

for concerts with natural music instruments, while

prolongation of reverberation time as well as enhance-

ment of spatial impression and loudness can be

achieved by means of electroacoustical systems of elec-

tronic architecture (see Section 7.4).

To a greater extent sound systems are used here to

cover speech amplification and the needs of modern

rock and pop concerts.

Table 7-5. Interrelation Between Utilization Profile
and Acoustical Measures

Utilization Profile Scope and Quality of the

Acoustical Measures

Very

High

High Medium Low Very

Low

Pure concert hall x

Pure opera house x

Multigenre theater x

Multifunctional hall, also for

modern music

x

Open air theater x

Club and bar areas, jazz clubs x

Auditoriums for speech x

Lecture and classrooms x