Laboratory Measurement of the Acoustical Performance of Body Cavity Filler Materials
This SAE Recommended Practice describes a laboratory test procedure for measuring the acoustical performance of a system consisting of a body cavity filler material formed into a rectangular cross-section channel. Materials for this test may include both heat reactive and chemically reactive products, with or without a nylon or other shelf to simulate a baffle in an application, or a combination of body cavity filler and aluminum foil to enhance the performance. These materials are commonly installed in transportation systems such as ground vehicles, and thus reduce the noise propagation through the rails, rockers, and pillar/posts.
This document is intended to rank order the acoustical performance of materials for application on channels using general automotive steel, such that the effects of sealing of pinch welds in addition to the material could be easily evaluated. The acoustical performance is expressed in terms of insertion loss (IL) which is described below. The test procedure described here is based on the method described in SAE J1400. However, this document differs from the SAE J1400 method in that the J1400 measures sound transmission loss, and this document measures IL of body cavity materials in a cavity.
Rationale: Increased use of cavity filler materials on rockers, pillars, posts and other cavities has resulted in the need to develop a standardized procedure for rank ordering the performance of these materials in a controlled environment in the laboratory using a channel that simulates the application.