Test procedure and automatic system for sound insulation measurement using the sound intensity method

Abstract

A test procedure has been developed for sound insulation measurements using the sound intensity method. The basis of the procedure is from international standards ISO 140-3 and ISO 9614-1. For specimens that are sound absorbing on the receiving room side, the transmitted intensity will be underestimated if the extraneous sound intensity "caused by flanking or sound leaks… is high. A flanking ratio check is included in the test procedure to maintain accuracy within desired limits. The consideration of the field nonuniformity indicator, F 4 , in the test procedure was also found necessary. Seals at the edges of movable components of sound isolating structures, for example doors, are often poorly designed and manufactured. Sound leaks increase the value of the field indicator F 4 because of inhomogeneous sound transmission. Improving the seal of finished products is not possible in the test situation. For F 4 to fall in the acceptable range the number of measurement points may have to be increased enormously. The test procedure can be applied both to laboratory and field measurements. The main advantage of the new sound intensity method is the ability to locate sound leaks in the test object. This allows a customer-friendly mechanism for product development. Another advantage is that the laboratory facility can be much lighter than for the conventional method while maintaining the same limit for the maximum measurable sound reduction index. An automatic two-dimensional robot scanning system was used for exact positioning of the intensity probe. © 1997 Institute of Noise Control Engineering. †S0736-2501"97…00502-X ‡

Sound Insulation of Doors—part 2: Comparison Between Measurement Results and Predictions

“…The measurements were carried out according to the principles of the new ISO/DIS 15186-1: 1998 using the sound intensity method and point-to-point measurements [2,3]. The sound intensity method is very appropriate for testing of doors because the sound #ow through the door, especially through the sound leaks, can be localized.…”

Sound Insulation of Doors—part 1: Prediction Models for Structural and Leak Transmission

“…Jones used a simpli"ed model for estimating the e!ect of sound leaks on the total sound insulation of partitions [4]. Hongisto et al presented some sound intensity #ow patterns of doors obtained by a two-microphone intensity method [5]. The sound leaks could be easily located by using discrete point-by-point measurements.…”