Papers Gallery

After determining the cut-off frequency, proper isolator should be selected for precision sound power level and sound level measurements. Anechoic chamber is fully exposed in industrial environment where unwanted sounds due to vibrations of machineries, which should be minimized by applying proper isolators. In the chamber not only, air born sound but structure sound affects the required free field condition. The proper isolating system depends on the total mass of the chamber. Vibration isolators are categorised based upon the commercial applications as follow:
Neoprene mounts, resilient pads, and a combination of a steel spring and neoprene pad. With different loads and static deflection, isolators are available in the market. The selection of the isolators is recommended by the manufacturers as well as ASHRAE. Several isolators are categorized by the type W, WSW, type N, ND, type V, O, OR, AS, type IS, CI, R, etc.
Isolation pads, generally type W, WSW, of felt, cork, neoprene impregnated fiberglass, or ribbed neoprene sandwiched by steel plates, having deflection of 1 mm, are used for high frequency applications. Neoprene mounts, type N, ND, are the individual mounts, having deflection about 6mm to 10 mm. In neoprene mounts, there is integral plate with taped holes for bolting to walls and floor. These types of isolators are used to support floating floors such as recording studio. A steel spring, type V, O, OR, is the most common isolator particularly for low frequency application. The deflection of spring is about 8 cm. For the design application, spring isolators must be loaded properly. Air mounts, AS, consists of neoprene bladder filled with compressed air. Disadvantage of the air mount isolator is that adequate air pressure should be kept with air source, along with periodic maintenance to see leakage of air. Air mounts provide larger static deflection than spring isolators with easy level adjustment. Support frames, type IS, CI, R, are used to support the load of the object, when the internal frame is not sufficient to take a point load. In Integral steel, Concrete inertial and rail frame bases, the structural deflection to spring deflection should be less than 1:8 under the equipment load.