Acoustics

NIC - NOISE ISOLATION CLASS

A single number rating derived from a standardized ASTM field acoustical test procedure. The test is based on measurement of sound pressure lever differences on each side of the field installed product, adjusted to compensate for ambient noise levels. No adjustment of the value is made to compensate for sound absorption in the “receiving room". Thus, the result is comparable to that perceived by the human ear. A NIC rating of 40 is considered very good for an operable wall. As with STC, the higher the rating the better the operable wall is at stopping sound transmission.

Acoustical Engineers consider NIC measurement the most utilitarian and widely used method of determining the sound reducing effectiveness of operable walls. The NIC value, being determined by field testing the actual product purchased for use by the Owner/Operator, usually predicts Customer Satisfaction. A further advantage of field measurement of NIC is the ability to locate, define and correct sound leakage not related to the operable wall. Examples would be holes in sound barrier above ceiling, or common ductwork or conduit.

AEC considers field measurement of NIC, either optional or mandatory testing, to be the way to determine and control acoustical effectiveness of operable walls. It is recommended that one should not rely on STC to predict Customer Satisfaction.