Berndt Zeitler

Methods to control low frequency impact noise in wood‐frame construction

The control of low frequency impact noise is of great importance in Japan and Korea. For impact noise rating, both countries use standardised heavy and soft impactors that inject high levels of low frequency power into a wood‐frame floor due to the high force applied and “good” impedance match between the source and the floor. This paper reports on a parametric study designed to confirm the important parameters for controlling low frequency impact noise and how these parameters are affected by changes to construction details. The paper shows that increasing the drive point impedance floor surface while minimising the structural coupling between the gypsum board ceiling and the structural framing (joists) are important elements. Additionally, a well‐designed floor topping can be very effective when applied to a suitable floor. The paper presents data to show the relative importance of direct and flanking transmission paths. Furthermore, it is shown that repeated impacts by the Bang Machine physically chang...

Change in Canada’s national building code—Overview of new requirements and of projects supporting the change

The proposed 2015 edition of the National Building Code of Canada sees a major change in sound insulation requirements. Instead of prescribing requirements for the separating assembly only (in terms of STC values), the Code now sets requirements for the sound insulation performance of the complete system (in terms of Apparent Sound Transmission Class (ASTC) values), including flanking sound transmission. The National Research Council Canada is actively supporting the change in the Code by conducting various projects with industry associations from different construction sectors, in order to provide tools, guidance, and the necessary data for compliance. This presentation provides an overview of the new requirements and of the different paths to compliance. Furthermore, various projects conducted at the National Research Council Canada to support the Code change are presented, including tools and guidance to help practitioners. Detailed descriptions of two of the projects are given in two complementary pre...

Change in Canada’s national building code—Assessing flanking sound transmission in steel-framed constructions

The proposed 2015 edition of the National Building Code of Canada sees a major change in sound insulation requirements. Instead of prescribing requirements for the separating assembly only (in terms of STC values), the Code now sets requirements for the sound insulation performance of the complete system (in terms of Apparent Sound Transmission Class (ASTC) values), including flanking sound transmission. The National Research Council Canada is actively supporting the change in the Code by conducting various projects with industry associations from different construction sectors, in order to provide tools, guidance, and the necessary data for compliance. This presentation focuses on an ongoing joint project between the National Research Council Canada and the Canadian Sheet Steel Building Institute. In the project, the direct and flanking sound transmission in steel-framed assemblies are being investigated. In the presentation, an overview of the project is given, and updates on the current status of the i...

Change in Canada’s national building code—Assessing flanking sound transmission in concrete-masonry constructions

The proposed 2015 edition of the National Building Code of Canada sees a major change in sound insulation requirements. Instead of prescribing requirements for the separating assembly only (in terms of STC values), the Code now sets requirements for the sound insulation performance of the complete system (in terms of Apparent Sound Transmission Class (ASTC) values), including flanking sound transmission. The National Research Council Canada is actively supporting the change in the Code by conducting various projects with industry associations from different construction sectors, in order to provide tools, guidance, and the necessary data for compliance. This presentation focuses on a joint project between the National Research Council Canada and the Canadian Concrete Masonry Producers Association. In the project, the direct and flanking sound transmission in concrete masonry and hybrid building systems were investigated. For masonry walls in combination with concrete floors, the ASTC values were calculate...

Subjective evaluation of low‐frequency impact sounds on floor‐ceiling assemblies.

To investigate meaningful ratings and criteria for the acoustical performance of building partitions, it is necessary to understand the subjective judgments of listeners when hearing transmitted or radiated sounds. Impact sounds on floors caused by footstep noise (walking, running, etc.) are particularly bothersome and are not well characterized. A series of recordings of the sound radiated into the room below a floor‐ceiling test assembly when an impact occurs on the topside of the assembly (floor surface) is ongoing. The primary impact sources considered are real adult walkers, and a heavy rubber ball, standardized in JIS A 1418‐2. The binaural recordings are presented to listening test participants, who rate subjective attributes of the sounds such as annoyance. In this way the floor‐ceiling test assembly is rated (and can be ranked) subjectively, and metrics derived from purely physical measurements can be assessed and interpreted. Preliminary results from measurements on a range of lightweight wood f...