Acoustics for Auditoriums and Concert Halls 1477.1 Introduction
With musical or spoken performances in auditoriums
and concert halls, acoustic evaluation is mainly based
on the subjective perception of audience and
performers. These judgements are generally not based
on defined criteria, but characterize the sensed tonal
perception. Besides the secondary factors influencing
the overall acoustic impression like, for instance,
comfortableness of the seats; air conditioning; interfer-
ence level; and optical, architectural, and stylistic
impression, it is especially the expectation of the
listener that plays a significant role for the acoustic
evaluation. If a listener in a classical concert is sitting
next to the woodwind instruments but hears the brass
instruments much louder, even though he cannot see
them, his expectations as a listener, and thus the acous-
tics are off. Numerous subjective and objective
room-acoustical criteria were defined and their correla-
tion determined in order to objectify these judgments.
However, these individual criteria are closely linked
with each other and their acoustic effects can neither be
exchanged nor individually altered. They become effec-
tive for judgment only in their weighted totality. The
judgment of the performers, on the other hand, can be
regarded as a kind of workplace evaluation.
Only the musician, singer or speaker who feels
completely at ease with all fringe factors will also praise
the acoustical quality. The main factors judged here are
the sound volume and the mutual listening, which is
also responsible for the intonation. An acoustically
adequate response from the auditorium has to be real-
ized for the performers so that this positive correspon-
dence supports the overall artistic experience. The
overall acoustic impression of his own work as it is
perceived in the reception area plays a very subordinate
role for the performer. What is important for him,
however, are rehearsal conditions where the acoustics
are as close as possible to those of the actual perfor-
mance and acoustical criteria that depend as little as
possible on the occupation density both in the audience
area as well as in the platform area.
Generally, a performance room must not show any
disturbing reflection characteristics like echo effects or
flutter echoes. All seats have to guarantee a good audi-
bility that is in good conformity with the auditory
expectation. This requires a balanced sound of high
clarity and an adequate spaciousness. Localization shifts
or deviations between acoustical and visual directional
impression must not occur. If the room is used as a
concert hall, the spatial unity between the auditorium
and the platform areas has to be maintained in order to
avoid sound distortions.
Based on these considerations and well-founded,
objective measurement technical examinations and
subjective tests, partially in reverberation-free rooms
within artificially generated sound fields, it is possible to
define room-acoustical quality criteria that enable an
optimum listening and acoustical experience in depen-
dence on the usage function of the room. The wider the
spectrum of usage is, the broader is the limit of the desir-
able reference value ranges of these criteria. Without
extensive variable acoustical measures—also electronic
ones—only a compromise brings about a somewhat
satisfactory solution. It stands to reason that this
compromise can only be as good as the degree in which
the room-acoustical requirements coincide with it.
A precondition for an optimum room-acoustical
design of auditoriums and concert halls is the very early
coordination in the planning phase. The basis here is the
establishment of the room’s primary structure according
to its intended use (room shape, volume, topography of
the spectators’ and the platform areas). The secondary
structure that decides the design of the structures on the
walls and ceilings as well as their acoustic effectiveness
has to be worked out on this basis. A planning method-
ology for guaranteeing the room-acoustical functional
and quality assurance of first-class concert halls and
auditoriums as well as rooms with a complicated
primary structure is reflected in the application of simu-
lation tests by means of mathematical and physical
models (see also Chapter 35 and Section7.3.1).7.2 Room-Acoustical Criteria, RequirementsThe acoustical evaluation by listeners and actors of the
acoustical playback-quality of a signal that is emitted
from a natural acoustic source or via electroacoustical
devices, is mostly very imprecise. This evaluation is
influenced by existing objective causes like disturbing
climatic, seating, and visibility conditions as well as by
subjective circumstances like, for instance, the subjec-
tive attitude and receptiveness towards the content and
the antecedents of the performance. Very differentiated
is the subjective rating of music, where the term good
acoustics is defined, depending on the genre, as a suffi-
cient sound volume, a good time and register clarity of
the sound, and a spaciousness that meets the composi-
tion. Timbre changes that deviate from the natural-
timbre of the acoustic sources and from the usual
distance dependence (high-frequency sounds are less
effective at a larger distance from the place of perfor-
mance than at closer range) are judged as being unnat-
ural, if traditional music is concerned. These
experiences determine also the listening expectation for