Room Acoustics 84529.2.1 External Airborne Noise
Here we are typically concerned with noise from local road traffi c, aircraft, and railways.
Any of these sources can generate levels of over 100 dB at low frequencies at the external
facade of a building. Controlling such high levels of low-frequency noise is extremely
diffi cult and costly. Therefore, if possible, when planning a sensitive acoustic area such as
a studio, it is obviously preferable to avoid locations or buildings exposed to high external
levels of noise. An extensive noise survey of the proposed site is therefore essential.
Wherever possible the walls to a studio or control room should not form part of the
external envelope of the building. Instead a studio should be built within the main body
of the building itself so a buffer area between the studio and external noise source can
be created, for example, by corridors or offi ces or other noncritical areas. Similarly, it
is not good practice to locate a studio on the top fl oor of a building. However, if it is not
possible to create suitable buffer areas, a 1-m minimum separation should be created
between external and studio walls or roof and ceiling etc.
29.2.2 Internally and Locally Generated Noise
Apart from being transmitted by sound pressure waves within the air, noise can also be
transmitted by the building structure itself. Structural noise can be induced either directly
by the vibration of the structure, for example, by locating the building over or adjacent
to a railway or underground train line, or sound pressure waves (particularly at low
frequencies) can cause the structure itself to vibrate. Again, the best method of control is
to separate the sensitive areas from such potential noise sources as structural isolation is
required. One solution is to spend the available budget on the equipment of rubber pads,
or literally steel springs if really effective low frequency isolation is required. However,
the best solution is to choose the site carefully in the fi rst place and spend the available
budget on the equipment and acoustic fi nishes rather than on expensive structural
isolation.
If the studio is to be built in a building with other occupants/activities, again a thorough
survey should be conducted to establish any likely sources of noise, which will require
more than usual treatment (e.g., machinery coupled into the structure on fl oors above or
below the studio. This includes lifts and other normal “ building services ” machinery such
as air conditioning plant, etc.).