Standards Development

Scope

This document specifies methodology for qualifying acoustic spaces as anechoic and hemi-anechoic spaces meeting the requirem e nt s of a free sound field.

This document specifies discrete-frequency and broad-band test methods for quantifying the performanc e of anechoic and hem ianechoic spaces, defines the qualification procedure for an omni-directional sound source suitable for free-field qualification, gives details of how to present the results and describes uncertainties of measurement.

This document has been developed for qualifying anechoic and hemi-anec hoic spaces for a variety of acoustical measurem ent purposes. It is expected that, over time, various standards and test codes will refer to this document in order to qualify an anechoic or hemi-anec hoic space for a particular measurem ent. Annex D provides guidelines for the specification of test parameters and qualification criteria for referencing documents.

In the absence of specific requirements or criteria, Annex A provides qualification criteria and measurem ent requirements to qualif y anechoic and hemi-anec hoic spaces for general purpose acoustical measurements.

This document describes the divergence loss method for measuring the free sound field performanc e of an acoustic environm ent.

Purpose

This document describes the divergence loss method of measurem ent of performance of an environment designed to provide a free sound field or free sound field over a reflecting plane. An acoustical environment is a free sound field if it has bounding surfaces that absorb all sound energies incident upon them. This is normally achieved using specialized test environments, such as anechoic or hemi-anec hoic chambers. In practice, these provide a controlled free sound field for acoustical measurem ents in a confined spac e within the facility.

The purpose of this document is to promote uniformity in the method and conditions of measurem ent when qualifying free sound field environments. It is expected that the qualification procedures outlined in this document will be referred to by other International Standards and indust ry test codes. In such cases, these documents making reference to this document may specify qualification criteria appropriate for the test method and may require specific traverse paths.