Author: T. Kelsall
Canadian Acoustics - Acoustique Canadienne, September 2004
Abstract
Since 1978 MOE has used the equivalent sound level of urban hum, that amalgam of distant traffic and other sounds which forms the background noise in most urban and suburban areas, as the primary limit for assessing the noise impact from industry and other sound sources. This means that the limit to be used at a specific location is based on the sound actually received at that location, rather than an arbitrary number. This has made sense to industry, residents and consultants, who have used this limit for over 25 years. It has also been used in a Federal-Provincial guideline and many practical limits are found to be based indirectly on urban hum. In this paper, the origins of this limit are explored and some of the issues which were examined at that time and later are discussed. How urban hum behaves, how widespread it is and how it is used as a limit are also reviewed.
