Site selection
In selecting a site for an
auditorium, noise prevailing or Foreseeable in that area should be considered
for their effects on the acoustical conditions in the building. Some of the
important sources of objectionable noise are – automobile, traffic, railways,
airports, industries etc. The site selected should be in quietest surroundings
consistent with other requirements so that the audibility of speech and total
quality of music are not affected.
Volume
The volume of the room should
be in proportion to the intensity of sounds to be generated in it. In planning
the volume of the auditorium, height is of great importance than either or
breadth. This on account of the font that a small increase in height results in
the considerable increase in the volume. The following values may be taken as a
rough guide for deciding the volume of an auditorium.
1) Public
lecture halls – 2.8 to 3.7 m3 / person.
2) Musical
concert halls – 4.2 to 5.6 m3 / person.
3) Cinema
theatres – 3.7 to 4.2 m3 / person.
However, the best guide for
deciding the volume of a proposed auditorium would be the detailed study of an
existing auditorium used for the similar purpose.
Shape
The shape of the room is more
important consideration in the acoustic design of an auditorium at it governs
the acoustical defects like echo’s foci, dead spots etc. The volume is decided
on the total number of audience, where as the shape is to be geometrically
emerged in view of better audibility. Usually
the shape of the auditorium is impressed in terms of the ratio of height, width
and length of the hall. From the total number of seats to be provided in an
auditorium, total cubical contents can be worked out and then from the relevant
ratio, length width and height can be determined. The floor plan of the
auditorium may have many typical possible shapes, such as rectangular,
fan-shaped, horse-shoe, circular, oval etc.
Treatment of Interior Surfaces
Along with the overall shape
and size of the auditorium, the treatment of interior surfaces, i.e. ceilings
and side walls also plans an influential part in the acoustical design. The
ceilings and side walls should provide favourable reflections or reinforce the
sound that reaches the rear parts of a large auditorium. Ceiling splays and
spread outs and appropriately tilted portions of the ceiling can be arranged or
desired to reinforce the sound. The side walls should also be splayed or spread
out such that they help in reinforcing the sound by way of favourable
reflections. Plain side walls are normally found suitable.
