engleski

The design of an in-situ absorption measuring system using the Adrienne method

The Adrienne method, standardized in the CEN/TS 1793-5, is a frequently used measurement technique developed for outdoor in-situ measurements of sound reflection and airborne sound insulation. The data given in the standard was used as the basis for the design of a measuring system to be used for determining the absorption coefficient and sound insulation of noise barriers and built-in roofs and wall systems. In this paper the design process is described, specifically, solving of encountered construction problems and system optimization in order to reduce the measurement errors and to eliminate elements that introduce uncertainty. As stipulated in the standard, a fixed source-microphone combination has been achieved, in our case by mounting the microphone holder at the end of a bar kept tightly in position by cables attached to the loudspeaker cabinet. The unit is mounted on a swivel that allows variations of both azimuth and elevation in the range of &plusmn ; ; ; 40 degrees from the reference axis in 10-degree steps. The excitation signals used in the measurements included the MLS and the sine sweep. The post processing of the measured impulse responses for various rotation angles and source positions was done in Matlab, developed especially for the Adrienne method.

sound reflection; in-situ measurement; sine sweep

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