Sound isolation of an audiometric test room

Modifications were required to reduce sound levels in a former office so that the room would meet the ambient noise requirements for audiometric testing. Sound sources in the area included people in neighboring offices, transformers in a neighboring mechanical equipment room, ventilation ducts in the plenum above the room, and air‐conditioning vents. The transformers created harmonically related vibration tones in the concrete floor slab and walls that radiated sound into the proposed audiometric test room. Acoustical recommendations consisted primarily of building a vibration‐isolated room within the existing room (including a floating floor) and acoustically treating the ventilation system. Initial measurements revealed unexpectedly high sound levels that were the result of unintended (erroneous) structural connections between the inner and outer room. When these connections were cut, the room met the noise requirements.