The noise reduction of an enclosure is a property of the enclosure, the location of the sound source used to measure noise reduction, and the space in which the enclosure is placed. It is not a property of the enclosure alone, and its measurement under different conditions can be expected to give different results. When the noise reduction is measured in accordance with this test method, the sound source is outside the enclosure and the sound field outside the enclosure approximates a diffuse sound field. Measurements made in accordance with this test method can be expected to be reproducible from one laboratory to another.

The noise reduction measured in accordance with this test method may be used for the following purposes:

To rank the order of sound-isolating enclosures according to noise isolation class, NIC.

To estimate the highest one-third octave band sound pressure levels that can occur outside the enclosure without exceeding specified sound pressure levels inside the enclosure.

To estimate the one-third octave band sound pressure levels that will occur inside the enclosure with specified sound pressure levels outside.

The noise reduction measured in accordance with this test method may not estimate accurately the isolation that the enclosure will provide when it is used to isolate a noise source inside it from the space outside. The user should be cautious when using noise reductions measured by this test method to evaluate enclosures used to enclose noise sources.

Sound-isolating enclosures are frequently made from prefabricated modular panels. The noise reduction measured by this test method applies to the complete enclosure and not to individual panels from which it is made and cannot be used to infer the sound transmission loss of the individual panels.

Specifications for sound-isolating enclosures may include reference to noise reduction and noise isolation class measured in accordance with this test method.

1.1 This test method covers the reverberation room measurement of the noise reduction of sound-isolating enclosures.

1.2 The noise isolation class may be determined from the noise reduction measured in accordance with this test method.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.