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an approach might also be less costly than trying to keep sound levels uniformly low. “People can become finely attuned to the sounds that most disturb them, heightening their annoyance.” NOISE IMPACTS ON HEALTH 14 Are motorways the best spot for wind turbines? Wind turbine noise can be detected at low levels, even when it is heard alongside motorway traffic noise, a study finds. It is possible for louder motorways to drown out turbine noise, however. The participants in this listening experiment could easily detect wind turbine noise, but only once they knew it was present in recordings of environmental noise. Public annoyance with wind turbine noise is rising with the increasing number of turbines installed. Previous studies have suggested that people are more annoyed by wind turbines than other sources of environmental noise, such as road trafc, even if they are equally as loud. Research has also indicated that masking turbine noise with other sounds could reduce annoyance. Tis Belgian study adds to the body of research into turbine noise. Motorways have been proposed as good locations for turbines, partly because the trafc could help conceal turbine noise. Fifty people participated in a listening test in which they were asked to identify and detect wind turbine noise when heard alongside trafc noise. None of the participants held negative attitudes towards wind energy, and only one was particularly familiar with turbine noise. Te researchers frst played recordings of noise at realistic indoor sound levels (40 A-weighted decibels (dBA)) to participants while they read at leisure in an otherwise quiet room. At this stage, the participants did not know the true purpose of the study or that they were going to be played recorded noises. Tere were four types of recording: pure wind-turbine noise, pure motorway noise, combined motorway trafc and wind turbine noise, and combined local road trafc and wind turbine noise. Motorway noise was continuous, whereas local road noise was intermittent and individual vehicles could be heard driving past. Te researchers asked participants to rate how annoying they found the noise recordings, without telling them what the recordings actually were. Participants considered local road trafc recordings much more annoying than motorway and turbine recordings. Tere was little diference in annoyance levels for motorway and turbine recordings, whether in isolation or combined. Source: Van Renterghem, T., Bockstael, A., De Weirt, V., Botteldooren, D. (2013) Annoyance, detection and recognition of wind turbine noise. Science of the Total Environment. 456- 457: 333-345. DOI: 10.1016/j. scitotenv.2013.03.095. Contact: Timothy. Van.Renterghem@ intec.Ugent.be Temes: Environment and health, Noise When asked to name what they had heard, nearly all participants correctly identifed road trafc noise. Just under half said they had heard wind turbines. A number of incorrect answers were given, including air trafc (48% of respondents) and sea waves (28%). In a second stage of the experiment, the researchers explored how loud trafc noise would have to be in relation to turbines, to mask their noise efectively. Te participants were asked to deliberately listen for turbines in recordings, which had an overall volume of around 40 dBA, but with varying ratios of turbine and trafc noise. At this stage, the listeners easily detected turbine noise in combined recordings, now they knew it was present. Tose who detected it most easily tended to be the same people who had rated it as annoying in the frst part of the experiment. Listeners started to detect turbine noise when it was 23 dBA quieter than accompanying motorway noise. Te turbine noise’s acoustical energy was thus 200 times lower than the motorway’s. In contrast, turbines could be detected at all volumes when combined with local road trafc, which suggests that road trafc is not suitable for masking turbines. Te researchers caution that the study was small-scale and short-term; some patterns they observed here might be diferent if they had conducted a long-term study. “…turbines could be detected at all volumes when combined with local road traffic, which suggests that road traffic is not suitable for masking turbines.” KH-BA-14-001-EN-N Further Reading News Alert articles Traffic noise pollution mapped with new mobile phone app (Nov 2014) A new mobile phone application which can help monitor trafc-noise exposure is presented in a recent study. Te app, ‘2Loud?’, can measure indoor night-time noise exposure and, given large-scale community participation, could provide valuable data to aid urban planning, the researchers say. In an Australian pilot study, nearly half of participants who used the app found that they were exposed to potentially unhealthy levels of night-time noise. e.htm Both traffic noise and air pollution linked to stroke (Oct 2014) Road trafc noise and air pollution both increase the risk of having a stroke, recent research from Denmark suggests. Te results suggest that trafc noise is more strongly associated with ischaemic stroke, whereas only air pollution appears to be linked with more serious, fatal strokes. http://ec.europa.eu/environment/integration/research/newsalert/pdf/ 

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