Resource Documents: Technology (145 items)
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Simplified method for determination of “amplitude modulation” of audible and inaudible wind turbine noise
Author: Cooper, Steven
The operation of a wind turbine results in a series of pulses where there is a significant instantaneous increase in the amplitude of the pressure signal dependent upon the loading (power output and wind strength) of the wind turbine. Such amplitude variations can be significant. The modulation of the amplitude of the acoustic signature for wind turbines is often referred to as “amplitude modulation”. One method of assessment of the degree of amplitude modulation for a wind turbine used in the UK is complex, time-consuming and expensive to undertake. A simplified method has been developed that is not just restricted to the dBA level and can be used to cover both inaudible and audible dynamically pulsed amplitude modulation. This simplified analysis method is not just restricted to wind turbine noise but has uses for other pulsating noise sources. Investigation of recreational music and industrial noise sources that give rise to the generation of pulsations occurring at an infrasound rate using the simple methodology is discussed.
Steven Cooper, The Acoustic Group, Australia
Proceedings of the 23rd International Congress on Acoustics, 9–13 September 2019, Aachen, Germany: pages 920–927
Download original document: “A simplified method for determination of “amplitude modulation” of audible and inaudible wind turbine noise”
Influence evaluation of infrasound by using both of biological information and infrasound sensors in the vicinity of wind turbine facilities
Author: Nagamatus, Megumi; and Yamamoto, Masa-yuki
In recent years, wind power generation attracts attention. However, problem of low frequency sound generated by wind turbines and its influence on human beings have been gradually taken up in society. We investigated the influence of ultra-low frequency sound generated from wind turbines on human subjects/testers from both aspects of measurement of audible/infrasonic sound and multiple biometric information sensing systems. In the experiment outside, portable electroencephalographs and pulse wave sensors are used because only such small equipment can be used to perform biological information sensing outdoor, in the vicinity of a wind turbine facility. In order to calculate relax trends from the obtained biological information, a method based on previous analyses for obtaining relaxation degrees R is used. It is coming from the fact that content rate of each frequency band included in the electroencephalogram waveform varies depending on the human mental state in the brain wave. Also, in analyzing the heart beat wave, we used an analytical method to find stress degrees S by using the balance of autonomic nerve that can be calculated from the heart beat signal fluctuations. Here we would like to introduce the result using the above analyses methods for almost 30 examples.
Megumi NAGAMATSU, Masa-yuki YAMAMOTO
Kochi University of Technology, Japan
Proceedings of the 23rd International Congress on Acoustics, 9–13 September 2019, Aachen, Germany: pages 2992–2999
Author: Thorsson, Pontus
In most countries there are regulations of wind turbine sound level outdoors at dwellings. Often there are also regulations of the sound levels inside the dwelling, however not often directly aiming at wind turbine sound. The sound level indoors from wind turbines has attracted more interest in the latest years, and then especially in the low frequency region (up to 200 Hz). Studies on the in situ sound level difference between outside and inside of dwellings are however scarce. This paper presents the in situ measured sound level difference for two Swedish houses in rural locations, both using a loudspeaker and using the wind turbine sound as exciting signal. This is possible due to a 2 month long measurement series with simultaneous sound recordings outside and inside. The sound pressure level differences from the two methods are shown to differ substantially.
Pontus THORSSON, Akustikverkstan, Lidköping, Sweden
Proceedings of the 23rd International Congress on Acoustics, 9–13 September 2019, Aachen, Germany: pages 3826-3830
Download original document: “In situ measured facade sound insulation of wind turbine sound”
Denmark, Europe, Germany, Italy, Netherlands, Noise, Regulations, Technology •
Author: Marini, Martino; et al.
The enduring energy scenario leads to further promote the development of the exploitation of renewable energy sources. Recent European standards have been defining a path to reach in 2050 a level of decarbonization lower of 80% compared to 1990. Wind farms have been growing quickly for [the] last decade with individual wind turbines getting larger and larger. In addition to the benefits of containing greenhouse gas emissions and restraining the use of depletable resources, drawbacks have also appeared due to noise generation from wind turbines and adverse reaction of some nearby residents. The noise generated by wind turbines has a broad spectrum character but the low frequency noise causes special problems. It is a fact that in different European countries special laws have been adopted to impose noise limits and evaluation methods for the assessment of environmental low frequency noise from this kind of sound source. Other countries are still lacking specific rules but in the authorization procedure such analysis is required by environmental control agencies. The purpose of this study consists of comparing the assessment procedures currently used in different European countries for the prediction of low frequency noise from wind turbines and its propagation. The comparison of procedures gives a chance to put forward progressions in low frequency noise emission and reception.
Martino MARINI, DADU University of Sassari, Italy
Costantino Carlo MASTINO, Roberto BACCOLI, Andrea FRATTOLILLO, DICAAR University of Cagliari, Italy
Antonino DI BELLA5, DII University of Padova, Italy
Proceedings of the 23rd International Congress on Acoustics, 9–13 September 2019, Aachen, Germany: pages 1441–1446
Download original document: “Implementation of the issue of noise from wind turbines at low frequencies”