Perception and annoyance due to wind turbine noise--a dose-response relationship

Installed global wind power increased by 26% during 2003, with U.S and Europe accounting for 90% of the cumulative capacity. Little is known about wind turbines' impact on people living in their vicinity. The aims of this study were to evaluate the prevalence of annoyance due to wind turbine noise and to study dose-response relationships. Interrelationships between noise annoyance and sound characteristics, as well as the influence of subjective variables such as attitude and noise sensitivity, were also assessed. A cross-sectional study was performed in Sweden in 2000. Responses were obtained through questionnaires (n = 351; response rate 68.4%), and doses were calculated as A-weighted sound pressure levels for each respondent. A statistically significant dose-response relationship was found, showing higher proportion of people reporting perception and annoyance than expected from the present dose-response relationships for transportation noise. The unexpected high proportion of annoyance could be due to visual interference, influencing noise annoyance, as well as the presence of intrusive sound characteristics. The respondents' attitude to the visual impact of wind turbines on the landscape scenery was found to influence noise annoyance.     

Relationship between exposure to multiple noise sources and noise annoyance

Relationships between exposure to noise [metric: day-night level (DNL) or day-evening-night level (DENL)] from a single source (aircraft, road traffic, or railways) and annoyance based on a large international dataset have been published earlier. Also for stationary sources relationships have been assessed. Here the annoyance equivalents model concerning noise annoyance from combined sources and the underlying assumptions are presented. The model first translates the noise from the individual sources into the equally annoying sound levels of a reference source, road traffic, and then sums these levels giving total level L. The annoyance from the combined sources is found by substituting exposure L in the road traffic exposure-annoyance relationship. The most important assumption, independence of the contributions of the sources, is discussed. It appears that independence will be violated substantially only due to the effect of the presence or absence of a quiet side of building which is not incorporated in the model. For use in practice the application of the model is broken down in five steps. The step by step procedure can be used for the assessment of the total noise level and the associated total annoyance on the basis of the DNL or DENL values of the individual sources.     

A comparison of models to predict annoyance reactions to noise from mixed sources

Many residential communities are exposed to environmental noise from a mixture of sources. A simple energy summation model provides a convenient method for predicting annoyance reactions in mixed source situations but there is research evidence that the validity of its application is questionable. In this paper various alternative models are discussed. Their predictive powers are compared by using noise and social survey data collected at residential sites in the vicinity of Toronto International Airport. Sites were purposely selected to represent a range of aircraft and road traffic noise combinations. Of the five models examined, the simple energy summation model gives the poorest prediction of average annoyance. The strongest predictions are achieved by using independent effects and energy difference models. The implications of the results for predicting annoyance reactions to mixed sources are considered.     

Pressure Leq and multiple noise sources: A comparison of exposure-response relationships for railway noise and road traffic noise

Exposure-response relationships vary with different noise sources when conventional L_eq is used as the noise exposure measure. Further, reported annoyance to multiple noise source environments can be higher than predicted by conventional L_eq. Pressure L_eq is proposed as a superior unified noise index and some evidence is presented in support of this proposal.     

Self-reported sleep disturbances due to railway noise: exposure-response relationships for nighttime equivalent and maximum noise levels

The objective of the present survey was to study self-reported sleep disturbances due to railway noise with respect to nighttime equivalent noise level (L(p,A,eq,night)) and maximum noise level (L(p,A,max)). A sample of 1349 people in and around Oslo in Norway exposed to railway noise was studied in a cross-sectional survey to obtain data on sleep disturbances, sleep problems due to noise, and personal characteristics including noise sensitivity. Individual noise exposure levels were determined outside of the bedroom facade, the most-exposed facade, and inside the respondents' bedrooms. The exposure-response relationships were analyzed by using logistic regression models, controlling for possible modifying factors including the number of noise events (train pass-by frequency). L(p,A,eq,night) and L(p,A,max) were significantly correlated, and the proportion of reported noise-induced sleep problems increased as both L(p,A,eq,night) and L(p,A,max) increased. Noise sensitivity, type of bedroom window, and pass-by frequency were significant factors affecting noise-induced sleep disturbances, in addition to the noise exposure level. Because about half of the study population did not use a bedroom at the most-exposed side of the house, the exposure-response curve obtained by using noise levels for the most-exposed facade underestimated noise-induced sleep disturbance for those who actually have their bedroom at the most-exposed facade.     

Relationship between low-frequency aircraft noise and annoyance due to rattle and vibration

A near-replication of a study of the annoyance of rattle and vibration attributable to aircraft noise [Fidell et al., J. Acoust. Soc. Am. 106, 1408-1415 (1999)] was conducted in the vicinity of Minneapolis-St. Paul International Airport (MSP). The findings of the current study were similar to those reported earlier with respect to the types of objects cited as sources of rattle in homes, frequencies of notice of rattle, and the prevalence of annoyance due to aircraft noise-induced rattle. A reliably lower prevalence rate of annoyance (but not of complaints) with rattle and vibration was noted among respondents living in homes that had been treated to achieve a 5-dB improvement in A-weighted noise reduction than among respondents living in untreated homes. This difference is not due to any substantive increase in low-frequency noise reduction of acoustically treated homes, but may be associated with installation of nonrattling windows. Common interpretations of the prevalence of a consequential degree of annoyance attributable to low-frequency aircraft noise may be developed from the combined results of the present and prior studies.     

Laboratory annoyance and different traffic noise sources

The acute annoyance reaction to different noise sources (lorries, aircraft, mopeds and trains) was investigated in a laboratory experiment. Students were exposed to different noise climates at noise levels 70 and 80 dB(A) for 25 minutes, and their reactions were subsequently assessed by using a questionnaire. Their general sensitivity to noise was also evaluated. The results demonstrated that L_eq gave the best correlation with annoyance. However, lorry noise was found to be less disturbing than aircraft noise at the same L_eq value. This was more pronounced if the different noises were compared at equal peak dB(A) levels. The results suggest that other factors such as the irregularity of the noise or the individual experience of the noise are of importance for the annoyance reaction. A relationship was found between the general annoyance score and annoyance reactions in the laboratory. Questionnaires could thus be a suitable tool for identifying noise sensitive persons.     

Exposure-effect relationships between road traffic noise annoyance and noise cost valuations in Valladolid, Spain

Environmental noise can produce negative effects on people’s health since it interferes with basic activities such as sleeping, resting, studying and communicating. These effects depend not only on the physical characteristics of the noise itself, but also on parameters associated to each person and each environment. It is thus important to study noise pollution from a quantitative point of view as well as a from the point of view of the annoyance that it produces in the population.We have conducted a social survey aiming to identify the main sound sources, evaluate the annoyance and analyse the main effects of noise on people. The survey was distributed to a sample of people living approximately in the corners of an imaginary 250 m grid placed over the map of the city of Valladolid (Spain). The same corners were used to perform in situ measurements for a noise city map.There are two main purposes for this research work: (1) we want to compare the objective noise measurements to the annoyance reported by the people in order to find some kind of dose-effect relationship, and (2) we want to analyse how the population of Valladolid evaluates noise reduction from an economical and social point of view.     

A criterion for predicting the annoyance due to higher level,low frequency noise

Annoyance due to low frequency noise is more qidespread than was at one time believed and case histories indicate that the annoyance is not predicted accurately by a dB(A) measurement. In this study the psychophysical magnitude estimation technique was used to determine if a predictor of low frequency noise annoyance, superior to the dB(A), could be found. Ten noise measures were considered and it was concluded tentatively that the dB(B) noise measure could be used to predict the annoyance due to levels of low frequency noise in the range 90–105 dB overall SPL.     

Comparing the relationships between noise level and annoyance in different surveys: A railway noise vs. aircraft and road traffic comparison

Annoyance expressed in a railway noise survey is compared with that in two road traffic and three aircraft surveys in order to determine whether responses to various environmental noises are similar or are source-specific. Railway noise is less annoying than other noises at any given high noise level. Railway noise annoyance increases less rapidly with increasing noise level. At high noise levels this gap in reactions averages about 10 dB but ranges from 4 dB to more than 20 dB. Comparisons between the findings in the different surveys can be made only after considering differences in noise index calculation procedures, human response measurement procedures and annoyance moderating conditions. The methodology for comparing surveys is examined. It is found that methodological uncertainties lead to imprecise comparisons and that different annoyance scales give different estimates of intersurvey differences.     

A procedure for the assessment of wind turbine noise

The noise assessment at the receivers due to wind turbines in operation is usually performed through outdoor measurements. Background noise and wind turbines noise (WTN) are related to wind speed and both contribute to the overall measured noise levels (environmental noise). Nevertheless, the relation between noise and wind speed is not easily predictable, especially when the wind farms are installed in hilly terrains, where the wind shear is truly remarkable. In Italy and in other countries, this kind of assessment is even more difficult to perform due to the national regulations that require to compute the difference between environmental and background noise levels with the same weather conditions. Thus, to get a reliable and approved measure of the residual noise it would be necessary to turn off the wind farm. This work suggests a technical procedure to simultaneously estimate the immission and the residual noise components measured nearby a wind farm when the residual noise is mainly generated by wind. This allows the evaluation of the noise impact produced by operational wind farms, without requiring the farm shut down. The method aims to be fairly straightforward, thus maintaining the required scientific basis to be used as an assessment procedure by consultants and public bodies.     

Experimental study of annoyance due to low frequency environmental noise

We have carried out a study of a particular environmental noise phenomenon which appears to be a cause of real and severe disturbance to certain people. The study has been based on field measurements and on laboratory studies and questioning involving two people who have suffered from this problem for some years. The disturbance is heard by them as a ‘throbbing’ sound and is particularly prevalent indoors, rather than out-of-doors.The study has indicated that the phenomenon arises with a broad band spectrum which lies close to the hearing threshold and which is unbalanced to the extent that the major stimulus occurs in the frequency range 20–100 Hz. It is suggested that the unbalanced spectrum may arise as a result of low frequency noise generated by distant industrial sources.     

Comparison between train noise and road noise annoyance during sleep

Sleep disturbance by train and road noises was studied through in situ physiological recordings on two groups of people submitted to both types of exposure. At different sites acoustical parameters do not influence sleep in the same way. In a quiet place, emergence is an important factor of disturbance, but in a noisy place, noise duration and peak level are acting with interaction to disturb sleep.     

Fuzzy models for accumulation of reported community noise annoyance from combined sources

Many scientists have investigated noise annoyance caused by combined sources. However, general annoyance reported in a social survey still has many unknown features. In this work the cognitive process involved in coming to a general noise rating based on a known, in context, rating of annoyance by particular sources is studied. A comparison of classical and fuzzy models is used for this. The new fuzzy linguistic models give a meaning to the successful strongest component or dominant source model that was used in previous work. They also explain to some extent particular features not included in that previous model. The variance not predicted by the fuzzy linguistic model is contrasted with personal data of the test subjects (age, gender, and education level) and the context of the question in the questionnaire. Only age seems to play a significant role.     

A case study of localization and identification of noise sources from a pitch and a stall regulated wind turbine

We have experimentally identified the noise-generation mechanisms of large modern upwind wind turbines (WTs). First, the sound measurement procedures of IEC 61400-11 were used in the field test, and noise emissions from two WTs were evaluated: a stall-controlled WT with powers of 1.5 MW and a pitch-regulated WT with powers of 660 kW. One-third octave band levels were normalized using the scale law for the velocity dependence of the inflow broadband noise and airfoil self-noise. The results showed that for the 1.5 MW WT, inflow turbulence noise was dominant over the whole frequency range. For the 660 kW WT, the inflow broadband noise did not contribute across the whole audible frequency range. The distribution of noise sources in the rotor plane was visualized using a beam-forming measurement system (B&K 7768, 7752, and WA0890) consisting of 48 microphones. The array results for the 660 kW WT indicated that all noise was produced during the downward movement of the blades. This finding was in good agreement with theoretical results obtained using an empirical formula that includes the effects of the convective amplification, directivity, and flow-speed dependence of the turbulence boundary-layer trailing edge noise. This agreement implies that this trailing edge noise is dominant over the whole frequency range in the case of the 660 kW WT.     

Road traffic noise - the relationship between noise exposure and noise annoyance in Norway

Exposure-effect relationships between the level of road traffic noise at the most exposed side of a dwelling's façade and the residents' reactions to road traffic noise have been estimated. The relationships are based on five Norwegian socio-acoustic studies featuring 18 study areas from two cities and a total of near 4000 respondents. The survey questionnaires distinguish between noise annoyance experienced right outside the apartment and when indoors. Exposure-effect relationships for all degrees of annoyance are estimated simultaneously from ordinal logit models. These predict road traffic noise annoyance when right outside the apartment and when indoors, respectively, as a function of the road traffic noise level outside the most exposed façade. Separate analyses indicate that Norwegians react stronger to road traffic noise than results from a recent compilation of socio-acoustic surveys would lead one to believe. People having inferior single glazing windows report higher indoor annoyance.     

A fuzzy rule based framework for noise annoyance modeling

Predicting the effect of noise on individual people and small groups is an extremely difficult task due to the influence of a multitude of factors that vary from person to person and from context to context. Moreover, noise annoyance is inherently a vague concept. That is why, in this paper, it is argued that noise annoyance models should identify a fuzzy set of possible effects rather than seek a very accurate crisp prediction. Fuzzy rule based models seem ideal candidates for this task. This paper provides the theoretical background for building these models. Existing empirical knowledge is used to extract a few typical rules that allow making the model more specific for small groups of individuals. The resulting model is tested on two large-scale social surveys augmented with exposure simulations. The testing demonstrates how this new way of thinking about noise effect modeling can be used in practice both in management support as a "noise annoyance adviser" and in social science for testing hypotheses such as the effect of noise sensitivity or the degree of urbanization.     

Relationship between Electroencephalogram variation and subjective annoyance under noise exposure

The relationship between Electroencephalogram (EEG) variation and subjective annoyance was investigated with 70 dBA white noise and pure tones at 160 Hz, 500 Hz and 4000 Hz being selected as exposed noise sources. The results indicate that when the duration of noise was less than 6 s, Average Power of Electroencephalogram (APEEG) varied irregularly. When the noise lasted for 5 min, the sum of the relative APEEG of θ wave and the relative APEEG of α wave increased with the subjective annoyance increasing under noise exposures. The maximum power of θ wave appeared in the frontal region, while the maximum power of α wave appeared in the occipital region. Up to the fifth minute after noise exposure, more than two APEEG maximums of θ wave appeared, and the time points of maximum occurrence shifted forwards slowly following the increase of exposed noise frequency. The interval between two time points of maximum occurrence was reduced with the increase of the exposed noise frequency.