This guide can be used to produce a specification for the acoustical performance of an enclosure.

This guide is intended for those familiar with basic concepts of acoustics.

Although this guide provides detailed guidance in matters relating to specification of acoustical enclosures, it is not a substitute for the experience and judgment of an acoustical or noise control professional.

This guide calls for measurements common within acoustical practice.

The more critical the performance requirements of the enclosure, the more the user should consider seeking the services of an acoustics or noise control professional.

The specifying of a sound-isolating enclosure has three sequential steps:

Determine the sound pressure levels that exist at specific locations prior to the introduction of the enclosure,

Note 1-In the case of new construction, the sound pressure level is often estimated from the sound power levels of noise-emitting equipment and a general description of the acoustical properties of the environment.

Determine the maximum permissible sound pressure levels that must exist at the same locations after the introduction of the enclosure, and

Determine the required enclosure level reduction. The required isolation is related to the difference between the sound pressure levels before and after the introduction of the enclosure.

Many specifications are for multiple enclosures or enclosures with multiple functions, or both. It is beyond the scope of this guide to provide detailed guidance for every possible combination. Separate specifications for each source-enclosure-receiver combination should be used in such a case.

The type of specification that should be selected depends both on the purpose of the enclosure and how crucial its performance is. In general:

If exceeding a particular maximum permissible sound pressure level spectrum would render the enclosure unsuccessful, a sound pressure level specification should be used.

This guide assigns all phases of acoustical design are delegated to the supplier. Compliance is usually more easily verified than with the level reduction method.

If the criteria for the success of the enclosure are less stringent or not related to a specific maximum permissible spectrum, a level reduction specification may be used.