TABLE OF CONTENTS There are four basic approaches to reducing noise in a listening room or a recording studio:
Locating the room in a quiet place
Reducing the noise energy within the room
Reducing the noise output of the offending source
Interposing an insulating barrier between the noise and the room
Locating a sound-sensitive area away from outside interfering sounds is a luxury few can enjoy because of the many factors (other than acoustical) involved in site selection. If the site is a listening room, which is part of a residence, due consideration must be given to serving the other needs of the family-at least if some degree of peace is to prevail. If the room in question is a recording or broadcast studio, it is probably a part of a multipurpose complex and the noises originating from business machines, air conditioning equipment, or foot traffic within the same building, or even sounds from other studios, may dominate the situation.
Protecting a room from street traffic noise is becoming more difficult all the time. It is useful to remember that doubling the distance from a noisy street or other sound source reduces the level of airborne noise approximately 6 dB. Shrubbery and trees can help in shielding from street sounds; a cypress hedge 2 ft thick gives about a 4 dB reduction.
The level of noise that has invaded a room by one means or another can be reduced by introducing sound-absorbing material...
