ACOUSTICS OF STUDIOS

A studio is a big room or a hall where sound is picked up by a microphone, and is either recorded or broadcast. It includes radio-broadcasting station, television station and sound recording studio. The basic requirements of such a studio are: (i) perfect sound proofing, and (ii) variable reverberation time, due to variable pitch and frequency of sound produced there.

The following points are noteworthy for the acoustic design of a studio.

1. The studio walls should be of rigid construction so as to completely insulate and exclude the external noise.

2. The studio should be rectangular in plan with ratio of height, breadth and length as 2:3:5. The ceiling should be flat.

3. The outer surfaces of wall should be reflective type, while the interior surfaces of walls, ceilings, floors, etc. should be of absorbent materials.

4. The noise level in the studio should be brought down to 20 to 30 dB.

5. Provision of windows should be minimum, to prevent transfer of noise from outside.

6. Air-conditioning machinery etc. should be completely isolated, and their noise should be completely insulated.

7. If there are more than one studios in a building; they should preferably be on the same floor. In no case should two studios be located one above the other; there should be a gap of atleast one floor.

8. The acoustic design of the studio should be such that echoes and near echoes are completely eliminated.

9. Heavy curtains and draperies should be used with advantage to control or regulate the time of reverberation.

10. Variable reverberation time can be obtained by providing hinged panels or shutters, with one surface of rotatable panel of absorptive material and the other of reflective material (Figure 1). Panels with hinge at the centre may also be used, having two different adsorbent materials on both the faces.

Figure 1. Hinged Panel

11. Reverberation time can also be varied by providing rotating cylinders in the ceiling of the studio. Each cylinder or drum (Figure 2) has three sectors, provided with three different absorptive materials. The cylinder can be rotated by rack and pinion arrangement, thus getting the required units of absorption for the desired reverberation time.

Figure 2. Rotable Cylinders