ASTM E492: Standard Test Method for Laboratory Measurement of Impact Sound Transmission Through Floor-Ceiling Assemblies Using the Tapping Machine
Standard: ASTM E492 - Standard Test Method for Laboratory Measurement of Impact Sound Transmission Through Floor-Ceiling Assemblies Using the Tapping Machine
Certification Required: Acoustical certification is currently not required by building codes, however a minimum IIC rating is required by the IBC and IRC codes for floor-ceiling assemblies in multi-family dwellings. IIC ratings on floor-ceiling assemblies can be required in certain types of buildings to meet the requirements in ANSI/ASHRAE/ICC/USGBC/IES Standard 189.1, LEED, ANSI/ASA S12.60 Guidelines for Schools, FGI Guidelines for Healthcare Facilities, and the International Green Construction Code. Some hotel chains do require minimum IIC ratings on floor-ceiling assemblies separating rooms in their hotels.
Scope: This test method covers the laboratory measurement of impact sound transmission of floor-ceiling assemblies using a standardized tapping machine. It is assumed that the test specimen constitutes the primary sound transmission path into a receiving room located directly below and that a good approximation to a diffuse sound field exists in this room. The data obtained from this test is used to calculate an Impact Insulation class (IIC) rating in accordance with ASTM E989.
Applicable Products: Floor coverings, floor underlayment products, suspended ceiling systems, gypsum concrete, insulation, gypsum board, wood and steel truss systems, subfloor products, resilient channels and other ceiling isolation systems are applicable for this test method. Floor-ceiling assemblies would need to be 10’ wide by 12’ long in order to fill the entire test frame.
Test Procedure: The test chambers consist of one reverberation room located directly above another reverberation room with a test opening between them. The product or assembly is installed into a test frame which is then placed in the opening between the test chambers. Care is taken that the only significant sound transmission path between the rooms is by way of the test specimen. The tapping machine is operated in four different locations on the floor (as specified in the standard) while the sound pressure levels are measured at four microphone locations in the room below. With the test specimen in place, the sound absorption and the background sound levels are also measured in the receiving room. The tapping machine sound pressure levels and the sound absorption in the receiving room are used to calculate the normalized sound pressure level, Ln at the standard 1/3 octave band frequencies from 100 to 3150 Hertz.
End Result: The test report will include the normalized sound pressure level from 100 to 3150 Hertz, and the IIC rating. The ISO 10140-3 test can also be performed and the normalized impact sound pressure level, Ln can be calculated in accordance with ISO 717-2. Sound transmission loss measurements may be conducted at some lower frequencies if requested in advance.
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