Acoustics

Chronic noise exposure in the spontaneously hypertensive rat

Health Canada conducts research to assess the potential health risks from noise as part of its role in administering the Radiation Emitting Devices Act, which governs the radiation safety of products that are imported and sold in Canada, including products emitting acoustical radiation (noise). Epidemiological studies conducted to date have suggested an association between the risk for developing cardiovascular disease (CVD) and long term exposure to transportation noise. Because stress is known to be a risk factor for developing CVD, some scientists hypothesize that noise may increase the risk of CVD by acting as a stressor, leading to changes in stress hormones. Laboratory studies have demonstrated that brief noise exposure is capable of triggering a stress response. However studies that investigate the effects of long term noise exposure are required. In this study, Health Canada assessed the effects of intermittent daily exposure to loud noise (87 dBA) for a period of 21 consecutive days in a rat strain that is known to be susceptible to developing high blood pressure, which is a form of CVD. The results of the study showed that noise exposure lead to lower body weight gain, had inconsistent effects on stress hormones, increased cortisol slightly, but had no effect on other hormones known to be influenced by stress. This pilot study did not provide strong evidence to suggest that long term exposure to loud noise would increase stress hormones that, if observed in humans, would potentially lead to CVD. These results, when considered together with other findings in this area, will be used to strengthen the advice that Health Canada provides on the health effects of noise exposure. The results of this research are published in the Journal Noise and Health (2017), 19: 213-221.

Prevalence of hearing loss among Canadians aged 20 to 79: Audiometric results from the 2012/2013 Canadian Health Measures Survey

Health Canada conducts research on the potential health effects of noise exposures. In this study, Health Canada partnered with Statistics Canada, on the 2012/2013 Canadian Health Measures Survey (CHMS), to learn more about what sources of noise Canadians were exposed to at work and during their leisure time. Hearing evaluations were carried out in a mobile clinic, which generated actual data from more than 3,000 Canadians for the first time. The results of the study estimate that 4.6 million adult Canadians, 20 to 79 years of age, have a measured hearing loss that could interfere with their ability to comprehend speech. Nearly two thirds of adults between the ages of 70 to 79 years were found to have measured hearing loss. Overall, 1 in 20 Canadian adults self-reported having a hearing loss, compared to 1 in 5 that were actually found to have some measurable hearing loss following a hearing exam. The results from this study will add to a growing scientific database related to the status of hearing health among Canadians, which can be used to support hearing conservation activities, track changes in hearing health over time and allow the impact of product or workplace noise on hearing health to be assessed. Research results are published in Health Reports, 26(7), 18-25, 2016.

Prevalence of hearing loss among a representative sample of Canadian children and adolescents, 3 to 19 years of age

Health Canada conducts research on the potential health effects of noise exposures. In this study, Health Canada partnered with Statistics Canada, on the recent 2012/2013 Canadian Health Measures Survey (CHMS), to learn more about what sources of noise Canadian youth were exposed to in their daily lives. Hearing evaluations were carried out in a mobile clinic, which generated actual data from approximately 2,000 Canadian children and adolescents for the first time. The results of the study indicate that an estimated 387,000 Canadian youth, 6 to 19 years of age, had some degree of measured hearing loss. There was some evidence that a significant number of children 3 to 5 years of age may be at risk of future hearing loss based on test results that may predict future hearing loss. These findings point to the importance of having hearing assessed at an early age, especially given the finding that two thirds of Canadian youth reported that they have never had their hearing tested by a health care professional. The results from this study will add to a growing scientific database related to the status of hearing health among Canadian youth, which can be used to support hearing conservation activities, track changes in hearing health over time and allow the impact of product or workplace noise on hearing health to be assessed. Research results are published in Ear & Hearing, Early ePub, Open Access, 2016.

Wind turbine sound pressure level calculations at dwellings

There is concern among some Canadians that living within the vicinity of wind turbines may have negative impacts on health. The Wind Turbine Noise & Health Study (WTNHS) was conducted by Health Canada, in collaboration with Statistics Canada and other external experts, in order to understand the effects of wind turbine noise on health and well-being. This paper describes the calculation of the sound pressure levels (SPL) from wind turbines at the homes of the 1238 survey participants in the WTNHS. Based on data provided by manufacturers, SPL was calculated outside of each home using internationally recognized standards. The SPL was manipulated using a method called C-weighting to emphasize the low frequency noise. For consistency, with the evaluation of most other noise sources, a method referred to as A-weighting was also used. Using C-weighting the SPL was consistently 15 dB higher than when using A-weighting, this difference confirmed that wind turbines produce low frequency noise. However, the simple consistent difference between A- and C- weighted SPL meant that neither weighting could provide any more information than the other. Typically, when siting wind turbines in Canada, the calculated SPL at dwellings assumes the wind speed is always constant. The same approach was used in the WTNHS. The wind speed chosen for analysis was 8 m/s, because this wind speed was associated with some of the highest sound levels from the wind turbines. In reality the wind does not blow continuously, so a realistic long term average SPL at the dwellings was calculated to be 4.5 dB lower than the SPL for constant wind speed. Ambient SPL was also estimated using guidance from the United States and Alberta, Canada. Published findings are consistent with previously released findings outlined on the Health Canada website. The results of this research are published in the Journal of the Acoustical Society of America (2016), 139(3): 1436-1442.

Wind turbine sound power measurements

There is concern among some Canadians that living within the vicinity of wind turbines may have negative impacts on health. The Wind Turbine Noise & Health Study (WTNHS) was conducted by Health Canada, in collaboration with Statistics Canada and other external experts, in order to understand the effects of wind turbine noise (WTN) on health and well-being. This paper provides experimental validation of the sound power level data provided by the wind turbine manufacturers for use in the WTNHS. Using international standards, sound power levels were measured from the 10 wind turbine models present in the WTNHS area. Measurements were consistent with the data provided by manufacturers. The measurements also allowed the manufacturers' data to be extended to lower frequencies. Including these low frequencies, the resulting frequency spectra were similar for all 10 turbine models; thereby making it more difficult to determine if there are any unique effects from low frequency noise. Published findings are consistent with previously released findings outlined on the Health Canada website. The results of this research are published in the Journal of the Acoustical Society of America (2016), 139(3): 1431-1435.

Estimating annoyance to calculated wind turbine shadow flicker is improved when variables associated with wind turbine noise exposure are considered

There is concern among some Canadians that living within the vicinity of wind turbines may have adverse health implications. The Wind Turbine Noise & Health Study (WTNHS) was conducted by Health Canada, in collaboration with Statistics Canada and other external experts, in order to understand the effects of wind turbine noise (WTN) on health and well-being. Although the primary objective of this study was to characterize the community response to WTN exposure, the results showed an increase in annoyance towards other features, including shadow flicker with increasing WTN levels. Shadow flicker is caused by the sun's movement behind the rotating blades of the turbine and is known to cause complaints among some communities situated near wind turbines. Health Canada scientists calculated the duration of shadow exposure at households in the WTNHS using WindPRO™ software. The WTNHS provided an opportunity to develop models that could be used to predict annoyance with shadow flicker. The results show a significant increase in annoyance when shadow flicker exposure was equal to, or greater than 20 minutes per day. In addition, it was found that some of the variables that were found to predict WTN annoyance were also significant predictors of shadow flicker annoyance. These included, but were not limited to, sensitivity to noise, concern for physical safety, being able to hear wind turbines from one's property, and other annoyances with wind turbine features (e.g. noise, blinking lights, visual, and vibrations). This paper concludes that although annoyance to wind turbine shadow flicker can be predicted by using only calculated WTN levels, there is a slight improvement in the strength of this prediction when calculated shadow flicker exposure models are used instead of WTN levels. This is further improved when other factors are considered. These results, when considered together with other findings in this area, strengthen the advice that Health Canada provides on the health effects of WTN exposure. The results of this research are published in the Journal of the Acoustical Society of America (2016), 139(3): 1480-1492.

Personal and situational variables associated with wind turbine noise annoyance

There is concern among some Canadians that living within the vicinity of wind turbines may have adverse health implications. The Wind Turbine Noise & Health Study (WTNHS) was conducted by Health Canada, in collaboration with Statistics Canada and other external experts, to understand the effects of wind turbine noise (WTN) on health and well-being, which includes community annoyance. Annoyance in this context refers to a subjective belief that for a long period of time (approximately 1year) WTN is considered to be very or extremely annoying. Scientists consider responses of this nature to reflect a state of "long term high annoyance". In this way, long-term high annoyance is considered to be more serious than a brief annoyance caused by an inconvenience, which may briefly disturb an activity. This paper presents multiple models for WTN annoyance as a way of identifying factors that predict this type of annoyance. The results show that although WTN levels on their own do predict annoyance, the strength of this prediction is substantially strengthened when other variables are included in the prediction models. These variables include, but are not limited to, other annoyance (i.e., visual, blinking lights, vibrations), reported sleep disturbance, sensitivity to noise and receiving personal benefits from having wind turbines in the area. It was also found that reporting to be concerned about one's physical safety associated with having wind turbines in the area was a predictor of WTN annoyance. This paper also compares the findings from the WTNHS to similar peer-reviewed studies published by other researchers in this area and those related to other transportation noise exposures. The comparison suggests that the community tolerance toward WTN is lower when compared to aircraft, rail and road traffic noise. This means that, at comparable sound levels, annoyance to WTN is greater than it is toward these other noise sources. The current paper provides a quantification of these differences. These results, when considered together with other findings in this area, strengthen the advice that Health Canada provides on the health effects of WTN exposure. The results of this research are published in the Journal of the Acoustical Society of America (2016), 139(3): 1455-1466.

Exposure to wind turbine noise: Perceptual responses and reported health effects

There is concern among some Canadians that living within the vicinity of wind turbines may have adverse health implications. The Wind Turbine Noise & Health Study (WTNHS) was conducted by Health Canada, in collaboration with Statistics Canada and other external experts, to understand the effects of wind turbine noise (WTN) on health and well-being. This paper provides a description of several self-reported measures of health and well-being in relation to WTN levels. A total of 1238 adults between the ages of 18-79 years participated in the study from areas in southern Ontario and Prince Edward Island (PEI). This paper shows that self-reported health effects, which included, but were not limited to, migraines, dizziness, tinnitus, sleep disorders, perceived stress levels, chronic pain and heart disease were all unrelated to WTN levels. This means that there was no pattern between reporting these health effects and where people lived in relation to wind turbines. However, people that lived in areas with higher WTN levels were more likely to be highly annoyed by several wind turbine features, including noise, shadow flicker, visual impacts, vibrations and the blinking lights on top of turbines that serve as aircraft warning signals. These results, when considered together with other findings in this area, strengthen the advice that Health Canada provides on the health effects of WTN exposure. The results of this research are published in the Journal of the Acoustical Society of America (2016), 139(3):1443-1454.

Self-reported and measured stress responses associated with exposure to wind turbine noise

There is concern among some Canadians that living within the vicinity of wind turbines may have adverse health implications. The Wind Turbine Noise & Health Study (WTNHS) was conducted by Health Canada, in collaboration with Statistics Canada and other external experts, to understand the effects of wind turbine noise (WTN) on health and well-being. Multiple measures of stress reported by and objectively measured in participants exposed to WTN were assessed in the WTNHS. The Perceived Stress Scale (PSS) is a widely used questionnaire designed to measure an individual's perception of stress during the previous month. Scores on the PSS were considered together with objectively measured blood pressure, heart rate and hair cortisol concentrations. Cortisol is a well-accepted stress hormone that increases with increasing stress. When the body releases cortisol in response to stress some of it will accumulate in hair and remain there as the hair grows. Because hair tends to grow at a rate of approximately 1cm every 30 days, the analysis of a 3 cm segment of hair collected in the WTNHS provided an estimate of cortisol production over the previous 90 days. Although this method has been used in several studies to assess long-term stress, the WTNHS represents the largest study in this area and the first to include this objective measure of stress in response to WTN. The results of the WTNHS showed that in the final models scores on the PSS, measures of blood pressure, heart rate and cortisol were all unrelated to WTN levels. These results, when considered together with other findings in this area, strengthen the advice that Health Canada provides on the health effects of WTN exposure. The results of this research are published in the Journal of the Acoustical Society of America (2016), 139(3):1467-1479.

Effects of Wind Turbine Noise on Self-Reported and Objective Measures of Sleep

There is concern among some Canadians that living within the vicinity of wind turbines may have adverse health implications. The Wind Turbine Noise & Health Study (WTNHS) was conducted by Health Canada, in collaboration with Statistics Canada and other external experts, to understand the effects of wind turbine noise (WTN) on health and well-being.  Health effects in the WTNHS were assessed by asking participants to respond to questions about their health, including questions related to their sleep. The Pittsburgh Sleep Quality Index (PSQI) is a validated questionnaire evaluating sleep quality over the previous 30 days, and was included as part of the questionnaire administered in the WTNHS. In addition to the questionnaire, a subsample of almost 700 participants in the WTNHS also wore a sleep watch for up to 7 days. The sleep watch was used to record movements providing an objective indication of different sleep parameters which included how often people awakened how long they slept and how long it took to fall asleep. Measures of sleep were assessed in relation to calculated WTN levels at participant’s households. The results of the WTNHS suggested that sleep was not influenced by exposure to WTN. Specifically, the responses to the sleep questions on the questionnaire and the data collected with the sleep watch were not found to be dependent on the level of WTN at the participant’s household. These results, when considered together with other findings in this area, strengthen the advice that Health Canada provides on the health effects of WTN exposure. The results of this research are published in the journal SLEEP, (January 2016); 39(1): 97-109.

An assessment of quality of life using the WHOQOL-BREF among participants living in the vicinity of wind turbines

There is concern among some Canadians that living within the vicinity of wind turbines may have adverse health implications. The Wind Turbine Noise & Health Study (WTNHS) was conducted by Health Canada, in collaboration with Statistics Canada and other external experts, to understand the effects of wind turbine noise (WTN) on health and well-being.  Researchers used internationally accepted methods to calculate WTN levels at participants’ dwellings. Health effects in the WTNHS were assessed by asking participants to respond to questions about their health, including questions related to their quality of life (QOL). The World Health Organization (WHO) developed an abbreviated version of their 100-item QOL questionnaire reducing the length to 26 questions. The shorter version is referred to as the WHOQOL-BREF and has been used in several QOL studies for many years. The WHOQOL-BREF provides an assessment of QOL in the following areas: Physical health, Psychological, Social relationships and Environment. In addition, there are two questions that evaluate overall QOL and Satisfaction with Health. The results of the WTNHS suggested that QOL was not influenced by exposure to WTN. This means that in the WTNHS the pattern of responses on the WHOQOL-BREF questionnaire did not depend on the level of WTN at the participants’ dwelling.  These results, when considered together with other findings in this area, strengthen the advice that Health Canada provides on the health effects of WTN exposure. Results of this research are published in the journal Environmental Research, 142 (2015): 227-238.

Self-Reported and Objectively Measured Health Indicators among a Sample of Canadians Living within the Vicinity of Industrial Wind Turbines: Social Survey and Sound Level Modelling Methodology

Health Canada provides advice on the potential health impacts of environmental noise, including that from wind turbines. In collaboration with Statistics Canada, Health Canada is conducting a multi-year research study to explore the relationship between wind turbine noise and possible health effects on individuals living near wind turbines. Wind turbine noise levels at dwellings selected for the study are modelled according to International standards and supported with specialised sound level measurements inside and outside a subsample of homes. An in-person computer based questionnaire evaluates participants' perception of community noise, general health, and sleep quality. In addition, the study includes objective measurements for blood pressure, stress and sleep. The overall research design for the study is complex and includes many different variables.  For this reason, and in order to provide a baseline reference in support of future publication of results, Health Canada has published the study’s elaborated methodology in the journal Noise News International (December 2013). The results of this research will strengthen the peer-reviewed scientific evidence base and, when considered together with other science in this area, support decisions, advice and policies regarding wind turbine development proposals, installations and operations in Canada.

MP3 Player Listening Sound Pressure Levels among 10 to 17 year old Students

Exposure to loud noise on a consistent basis can adversely affect one’s hearing. Health Canada is working to reduce the incidence of noise-induced hearing loss in Canada. In this study, Health Canada examined childrens’ exposure to noise from portable digital audio players. Estimates were made of daily exposure to sound from portable digital audio players. Subjects were students (93 males, 126 females) in the age range of 10 to 17 years. The exposures were estimated for each subject using a measurement of typical sound levels (i.e. headphones were placed on a mannequin with realistic rubber ears; measurements were detected by microphones placed where the eardrums would normally be) and the average daily duration of use. Based on these estimates 3.2% of subjects exceeded the common occupational noise exposure level limit in Canada of 85 A-weighted decibels (dBA) for 8 hours per day. When the subjects set their audio players to the maximum volume that they would use, it was estimated that the daily exposure for 77.6% of the students would be below the level for which there is no known risk of permanent hearing loss, 75 dBA for 8 hours per day. The results of this research can be used to assess whether new measures are needed to manage the potential risk from listening to MP3 players. Research results are published in the Journal of the Acoustical Society of America, 2011 Nov; 130(5): 2756-64.