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1.1 This practice covers the impulse response measurement method using sweep signals, and its use to determine two important room-acoustical quantities: the difference in sound pressure levels between two positions, as used for example in standards determining transmission loss; and decay curves, as used in standards determining the decay rate or reverberation time.

1.2 The practice shall be used in conjunction with test methods that use one or both of the quantities described in 1.1.

1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

5.1 ASTM standard test methods that involve sound attenuation and those test methods that involve absorption or decay rates use a noise signal to determine these quantities. The IR method using a sweep signal given in this standard practice can be referenced by these other standards to provide an alternative measurement technique. This alternative technique has the advantage of providing more reliable results in a shorter period of time.

5.2 The results obtained with the noise and IR method are considered identical to within the typical measurement uncertainty for the noise method under repeatability conditions. A mandatory validation procedure is given in this practice to ensure a correct implementation of the IR method when developing software or hardware according to the requirements in this standard.

5.3 To avoid ambiguity in the implementation of the IR method and to ensure consistent results across different users, this practice prescribes the values of methods and parameters to be used in the signal generation and post-processing. This is in contrast to similar standards describing this method, such as ISO 18233, which provide less guidance.