Research Highlights

Technical Series 02-108

Noise Isolation Provided by Gypsum Board Partitions

Introduction

In October 1995, the Institute of Research in Construction of the National Research Council of Canada published a summary report (internal report IRC-IR-693) containing the results, expressed in terms of Sound Transmission Class (STC), of 285 sound transmission loss tests performed on lightweight walls constructed with gypsum boards. In 1998, the Institute of Research in Construction published its internal report no 761, which is an extension of its IRC-IR-693 summary report. In the IRC 761 report, we can find the complete results expressed in terms of third octave sound transmission loss from 50 Hz to 6300 Hz of acoustical tests conducted on 350 gypsum wall compositions (the 285 compositions published in the summary report plus an additional 65) along with the physical properties of the materials and the methods used during the construction of the sample partitions. This database provided the basis for a broad general evaluation of sound transmission through gypsum board wall systems.

In July 2001, the CMHC commissioned MJM Acoustical Consultants Inc., to analyse the data contained in IRC report no 761, and to prepare the present report in which the main factors influencing the performance of gypsum board partitions are discussed. This report has been organized to reflect the respective influence, on the sound transmission loss of gypsum board partitions, of its four main components: the gypsum boards themselves, the studs and stud arrangements, the resilient furrings, and the sound absorptive materials inserted in the cavity.

Conclusions of the study

The following conclusions were reached:

Contribution to the construction industry

The first phase of this study completed by the Institute of Research in Construction provided a large database documenting the sound transmission loss provided by the gypsum board partition compositions commonly used. All the measurements have been conducted under the same acoustical conditions inside the acoustics laboratory of the National Research Council of Canada, using the most recent measuring methods, which makes it a very reliable database. In addition to acoustical data, the reports published by the IRC document the physical characteristics of the materials entering in the composition of the partitions, as well as the methods used to construct the partitions, which was rarely the case in the preceding studies.

Using the database created by the IRC, the present research project report highlighted the main factors influencing the acoustical performance of gypsum board partitions (the gypsum boards themselves, the studs and stud arrangements, the resilient furrings, and the sound absorptive materials inserted in the cavity) and hence to optimize the acoustical performance of these partitions in function of their composition and cost.

Project Manager: Jacques Rousseau jroussea@cmhc.ca

Research Consultants:
MJM Acoustical Consultants Inc., Montréal Michel Morin, Jean-Marie Guérin, Pascal Everton mmorin@mjm.gc.ca

1 Critical frequency:The lowest frequency at which the length of the bending waves in a material is the same as that of the sound waves in the air; it is at the critical frequency that a material irradiates sound most effectively.

2 TL - Transmission loss

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