Calculation of noise in residential environments

The DEFRA funded project “Human Response to Vibration in Residential Environments” investigates relationships between human response in residential areas, primarily in terms of annoyance, and combined effects from exposure to vibration and noise. This paper focuses on the results from the analysis of noise exposure in this study, in particular from construction work and railway traffic. The exposures for railway traffic noise sources were obtained and calculated according to a routine based on Calculation of Railway Noise (Department of Transport 1995) and “Additional railway noise source terms for 'Calculation of Railway Noise (2007)'” (Department of Transport 2007). On the other hand, exposure from construction work was calculated based on measurements of the various sources at different locations. This paper compares noise exposures from those sources in terms of level of noise, frequency content, distance from source to receiver, and the environment in which residents are exposed to noise and the reported annoyance. To conclude, the paper shows the relationships between noise exposure from the different vibration sources and annoyance. [Work funded by the Department for Environment, Food and Rural Affairs (Defra) UK]. INTRODUCTION Environmental noise is the effect of single or combined sources generating sound. Noise exposure, affecting residential environments, has its source in railway, construction, aircraft traffic, and road traffic. Additional to the effects from different noise sources, residential environments are also exposed, to a greater or lesser extent, to vibration. This combination of exposures has already been investigated in Sweden in a similar project called TVANE (Öhrström et al. 2008). TVANE also analyzed similar problems regarding combination of noise and vibration. This project "Human Response to Vibration in Residential Environments", funded by Defra, also investigated combined effects of exposure to noise and vibration. This paper outlines the process of calculation of noise exposure from different sources, such as railway traffic and construction work. Although some analysis regarding the exposure response relationship has been included, the detailed information of this topic, regarding combined effects, can be found in Technical Report 6 “Determination of Exposure-Response Relationships” (Woodcock et al. 2011.) BACKGROUND For the purposes of the project “Human Response to vibration in residential environments”, all sites were carefully chosen to fulfill the main objectives, which were to measure vibration in the vicinity of railway and construction sources. A great number of vibration measurements were conducted around the Midlands and North-west of 1 Calculation of Railway Noise (Department of Transport 1995) is denoted as CRN throughout this paper 10th International Congress on Noise as a Public Health Problem (ICBEN) 2011, London, UK 815 England. On the other hand, measurement of construction sources took place in South and Site B. Measurements of construction activities covered a process of building new light railway in Manchester. Variations were found in terms of the noise levels attributable to the different sources (construction and railway), although these variations were also observed in different locations of the same sources themselves. This paper presents the outline of the results from the noise measurements. For the details regarding the measurement of vibration, calculation of noise, and determination of exposure-response relationship, it is suggested the technical reports published by Defra are read (Sica et al. 2011; Woodcock et al. 2011). METHODOLOGY Noise metrics To express an overall noise exposure over a 24 h time period, a noise descriptor such as Lden has been chosen. It is defined in terms of average sound pressure level during daytime (07:00 19:00), evening (19:00 23:00) and night time (23:00 07:00) and imposes a 5 dB penalty during the evening and 10 dB penalty during the night time. Lden is calculated from the following formula                 /10 ( 5)/10 ( 10)/10 10 12 10 4 10 8 10 10log 24 day evening night L L L