Standard: ASTM E1414 - Standard Test Method for Airborne Sound Attenuation Between Rooms Sharing a Common Ceiling Plenum

Certification Required: Acoustical certification is currently not required by building codes, however the ceiling attenuation class (CAC) rating is required when classifying acoustical ceiling products in accordance with ASTM E1264. The CAC rating is also useful for architects and acoustical consultants that are designing offices with suspended ceilings in buildings

Scope: This test method utilizes a laboratory space so arranged that it simulates a pair of horizontally adjacent small offices or rooms separated by a partition and sharing a common plenum space. The partition either extends to the underside of a common plenum space or penetrates through it. In the prescribed configuration, special design features of the facility ensure that the only significant sound transmission path is by way of the ceiling and the plenum space. The data obtained from this test is used to calculate a ceiling attenuation class (CAC) rating in accordance with ASTM E413.

Applicable Products: Suspended ceiling systems that contain ceiling panels, and possibly luminaires and ventilation systems. The suspended ceiling systems for this test are approximately 15’ wide by 30’ long.

Test Procedure: Broadband noise is generated in the source room and travels through the source room ceiling into the plenum space and down into the receiving room. The space and time-averaged sound pressure levels are measured in both rooms simultaneously at five microphone locations. The ceiling attenuation (Dc) is the noise reduction between the source and receiving rooms where flanking transmission by all other paths are at least 10 decibels lower than the path through the ceiling and plenum. The sound absorption is also measured the receiving room so that the normalized ceiling attenuation (Dn,c) can be calculated.

End Result: The test report will include the normalized ceiling attenuation (Dn,c) values from 80 to 5000 Hertz, and the CAC rating.

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