Laboratory Floor Impact Testing
Laboratory Floor Impact Testing (ISO 16251-1)
Comet Test Bench Accelerometer Method by SINUS Messtechnik GmbH
The COMET Impact sound measuring test bench is a compact and controlled method for testing impact sound isolation, for comparing the sound impact performance of floor products under the same test conditions and for determining the improvement in impact sound isolation from changes to product material, or construction specifications.
The COMET impact sound measuring test bench is designed to provide a compact laboratory method to determine the sound impact isolation levels in accordance with the requirements of DIN EN ISO 16251-1.
In the past, testing of sound impact isolation required a laboratory which included two rooms, one above the other, with a size of 50 m³ each, or alternatively testing was conducted in-situ in buildings to demonstrate the relative performance of product A compared to product B, so that a selection could be made by the architect or owner.
Two room laboratory testing of sound impact isolation was very expensive and could be a disincentive to manufacturers who were interested in developing new floor products with satisfactory or improved sound isolation characteristics.
To assist small and medium sized manufacturers, the German PTB and the Forschungsinstitut für Leder und Kunststoffbahnen (FILK – German Research Institute for Leather and Plastic Sheeting) have developed a new compact method for testing sound impact isolation using a test bench that replaces the two-room laboratory test.
The COMET test bench consists of a 1.2m x 0.8m x 0.2m concrete slab which rests in a vibration-damped Euro-format steel rack. A standard sound insulation tapping machine is used for impact sound excitation. Two measurements are performed, one with and one without floor covering on the concrete slab.
The COMET Method utilizes multi-channel data acquisition instruments and uses accelerometers. The measurement method utilises a multi-channel measurement system and specifically designed software by SINUS Messtechnik GmbH.
The acceleration or velocity levels underneath the concrete slab are measured and the difference between the average accelerations or velocities is evaluated in accordance with the methods of DIN EN ISO 717-2. The results of the two-room and COMET methods show only very slight deviations with respect to floor coverings with local elastic deformation, such as PVC, carpet or linoleum. Laminate flooring exhibits larger deviations, since it does not deform locally.
The observed deviations are relatively minor, however, compared to the uncertainties of insitu building acoustic measurements.
For further information refer to the document PTB_COMET.pdf or the website of the federal test institute Physikalisch-Technische Bundesanstalt (PTB).
Model TM50 Tapping Machine, by SINUS Messtechnik GmbH
Model M1006 Tapping Machine, by CESVA Instruments
DIN EN ISO 717-2: Rating of sound insulation in buildings and of building elements – Part 2: Impact sound insulation
DIN EN ISO 16251-1: Laboratory measurement of the reduction of transmitted impact noise by floor coverings on a small floor mock-up
Design of the measuring station
Standard concrete floor model (developed by the PTB)
8 channel – measurement system, such as Soundbook; or laptop plus Expander, Apollo, Apollo Lite by SINUS Messtechnik GmbH
COMET software by SINUS Messtechnik GmbH
6 x accelerometers
Standard sound insulation tapping machine