ASTM E90-02 pdf free download.Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements.
1.1 This Lest method covers the laboratory measurement of airborne sound transmission loss of building partitions such as walls of all kinds, operable partitions. tloor-ceiling assemblies, doors, windows, roofs, panels, and other space-dividing elements.
1.2 Laboratory Accreditation—A procedure for accrediting a laboratory for performing this test method is given in Annex
A3.
3. Terminology
3.1 Definitions of the acoustical terms used in this test method are given in Terminology C 634. A few definitions of special relevance are repeated here for convenience only.
3.1.1 dffu.se sound field—the sound in a region where the sound intensity is the same in all directions and at every point.
3. 1 .2 direct sound field—the sound that arrives directly from a source without reflection.
3. 1 .3 flanking transmission—Lransmission of sound from the source to a receiving location by a path other than that under consideration—in this case other than through the test partition.
3.1.4 rei’erberuiion room—a room so designed that the reverberant sound field closely approximates a diffuse sound field, both in the steady state when the sound source is on, and during decay after the source of sound has stopped.
3. 1.5 reierbera,it sound field—the sound in an enclosed or partially enclosed space that has been reflected repeatedly or continuously from the boundaries.
3. 1 .6 sound transmission coefficient, T (dimension!ess)—of a partition, in a specified frequency hand, the fraction of the airborne sound power incident on thc partition that is transmitted by the partition and radiated on the other side. (Note that, unless qualified, this term denotes the sound transmission coefficient obtained when the specimen is exposed to a diffuse sound field as approximated, for example, in reverberation rooms meeting the requirements of this test method.)
3. 1 .7 sound transnission loss, TL—of a partition, in a specified frequency band, ten times the common logarithm of the reciprocal of the sound transmission coeflicient. The quantity so obtained is expressed in decibels.
3. 1 .7. 1 For the purposes of this test method, transmission loss is operationally defined as the difference in decibels between the average sound pressure levels in the reverberant source and receiving rooms, plus ten times the common logarithm of the ratio of the area of the common partition to the sound absorption in the receiving room (see Eq 12).ASTM E90 pdf download.