846 Chapter 29
29.2.3 Internal Noise Transfer
The biggest noise problem in most studios is noise generated or transmitted by the air
conditioning equipment. Studios must provide a pleasant atmosphere to work in, which,
apart from providing suitable lighting and acoustics, also means that the air temperature
and humidity need to be carefully controlled. Sessions in pop studios may easily last 12
to 15 h. The studio/control room must therefore have an adequate number of air changes
and suffi cient fresh air supply in order for the atmosphere not to become “ stuffy ” or fi lled
with cigarette smoke and so on.
It should be remembered that the acoustic treatments also tend to provide additional
thermal insulation and in studios with high lighting capacity (e.g., TV or fi lm) or where
a large number of people may be working, the heat cannot easily escape, but is contained
within the studio, requiring additional cooling capacity over that normally expected.
Large air conditioning ducts with low air fl ow velocities are therefore generally employed
in studios with special care being taken to ensure that the air fl ow through the room
diffuser grilles is low enough not to cause air turbulence noise (e.g., duct velocities
should be kept below 500 f t^3 /min, and terminal velocities below 250 ft^3 /min). Studios
should be fed from their own air conditioning plant, which is not shared with other parts
of the building.
Ducts carrying air to and from the studios are fi tted with attenuators or silencers to
control the noise of the intake or extract fans. Cross talk attenuators are also fi tted in
ducts that serve more than one area, for example, studio and control room, to prevent the
air conditioning ducts acting as large speaking tubes or easy noise transmission paths.
Studio air conditioning units should not be mounted adjacent to the studio but at some
distance away to ensure that the air conditioning plant itself does not become a potential
noise source. Duct and pipe work within the studio complex will need to be mounted with
resilient mountings or hangers to ensure that noise does not enter the structure or is not
picked up by the ductwork and transmitted to the studio.
Water pipes and other mechanical services ducts or pipes should not be attached to studio
or control room walls, as again noise can then be transmitted readily into the studio.
Impact noise from footfall or other movement within the building must also be dealt with
if it is not be transmitted through the structure and into the studio. A measure as simple as