Experimental Identification of Acoustic Emission Characteristics of Large Wind Turbines with Emphasis on Infrasound and Low-Frequency Noise

Jung, Sung Soo; Cheong, Cheolung; Shin, Su-Hyen; Cheung, Wan‐Sup

doi:10.3938/jkps.53.1897

Cited by 31 publications

(13 citation statements)

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“…Sugimoto et al (2008) reported a dominant spectral peak at 2 Hz with levels monitored over time reaching up to 100 dB SPL. Jung and Cheung (2008) reported a major peak near 1 Hz at a level of approximately 97 dB SPL. In most studies of wind turbine noise, this high level, low frequency noise is dismissed on the basis that the sound is not perceptible.…”

Section: Wind Turbine Noisementioning

confidence: 97%

Responses of the ear to low frequency sounds, infrasound and wind turbines

2010

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Infrasonic sounds are generated internally in the body (by respiration, heartbeat, coughing, etc) and by external sources, such as air conditioning systems, inside vehicles, some industrial processes and, now becoming increasingly prevalent, wind turbines. It is widely assumed that infrasound presented at an amplitude below what is audible has no influence on the ear. In this review, we consider possible ways that low frequency sounds, at levels that may or may not be heard, could influence the function of the ear. The inner ear has elaborate mechanisms to attenuate low frequency sound components before they are transmitted to the brain. The auditory portion of the ear, the cochlea, has two types of sensory cells, inner hair cells (IHC) and outer hair cells (OHC), of which the IHC are coupled to the afferent fibers that transmit “hearing” to the brain. The sensory stereocilia (“hairs”) on the IHC are “fluid coupled” to mechanical stimuli, so their responses depend on stimulus velocity and their sensitivity decreases as sound frequency is lowered. In contrast, the OHC are directly coupled to mechanical stimuli, so their input remains greater than for IHC at low frequencies. At very low frequencies the OHC are stimulated by sounds at levels below those that are heard. Although the hair cells in other sensory structures such as the saccule may be tuned to infrasonic frequencies, auditory stimulus coupling to these structures is inefficient so that they are unlikely to be influenced by airborne infrasound. Structures that are involved in endolymph volume regulation are also known to be influenced by infrasound, but their sensitivity is also thought to be low. There are, however, abnormal states in which the ear becomes hypersensitive to infrasound. In most cases, the inner ear’s responses to infrasound can be considered normal, but they could be associated with unfamiliar sensations or subtle changes in physiology. This raises the possibility that exposure to the infrasound component of wind turbine noise could influence the physiology of the ear.

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Section: Wind Turbine Noisementioning

confidence: 97%

Responses of the ear to low frequency sounds, infrasound and wind turbines

2010

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“…It was argued that insulation measurements of town houses (unpublished data) had shown better sound insulation than the buildings used in the background material for the regulation of noise from high-speed ferries. 35 Lee et al 36 and Jung et al 37 measured noise from two upwind turbines of respectively 660 kW and 1.5 MW. The A-weighted noise increased with wind speed for the 1.5 MW turbine, whereas it was fairly constant over most of the operating range for the 660 kW turbine.…”

Section: B Previous Studiesmentioning

confidence: 99%

Low-frequency noise from large wind turbines

Møller

Pedersen

2011

The Journal of the Acoustical Society of America

167

109

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As wind turbines get larger, worries have emerged that the turbine noise would move down in frequency and that the low-frequency noise would cause annoyance for the neighbors. The noise emission from 48 wind turbines with nominal electric power up to 3.6 MW is analyzed and discussed. The relative amount of low-frequency noise is higher for large turbines (2.3-3.6 MW) than for small turbines (≤ 2 MW), and the difference is statistically significant. The difference can also be expressed as a downward shift of the spectrum of approximately one-third of an octave. A further shift of similar size is suggested for future turbines in the 10-MW range. Due to the air absorption, the higher low-frequency content becomes even more pronounced, when sound pressure levels in relevant neighbor distances are considered. Even when A-weighted levels are considered, a substantial part of the noise is at low frequencies, and for several of the investigated large turbines, the one-third-octave band with the highest level is at or below 250 Hz. It is thus beyond any doubt that the low-frequency part of the spectrum plays an important role in the noise at the neighbors.

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“…As short pulses produce this type of sound, harmonics of this main frequency are usually observed. Jung et al [2008] describe the observations of TS (f TS = 0.863 Hz and ω = 1.806 rad/s or 17.3 revolutions per minute (rpm)) from a 1.5 MW turbine at short distance (98 m) where up to the eighth harmonic was observed.…”

Section: Wind Turbine Soundmentioning

confidence: 99%

On infrasound generated by wind farms and its propagation in low‐altitude tropospheric waveguides

et al. 2015

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Infrasound from a 60‐turbine wind farm was found to propagate to distances up to 90 km under nighttime atmospheric conditions. Four infrasound sensor arrays were deployed in central New Mexico in February 2014; three of these arrays captured infrasound from a large wind farm. The arrays were in a linear configuration oriented southeast with 13, 54, 90, and 126 km radial distances and azimuths of 166°, 119°, 113°, and 111° from the 60 1.6 MW turbine Red Mesa Wind Farm, Laguna Pueblo, New Mexico, USA. Peaks at a fundamental frequency slightly below 0.9 Hz and its harmonics characterize the spectrum of the detected infrasound. The generation of this signal is linked to the interaction of the blades, flow gradients, and the supporting tower. The production of wind‐farm sound, its propagation, and detection at long distances can be related to the characteristics of the atmospheric boundary layer. First, under stable conditions, mostly occurring at night, winds are highly stratified, which enhances the production of thickness sound and the modulation of other higher‐frequency wind turbine sounds. Second, nocturnal atmospheric conditions can create low‐altitude waveguides (with altitudes on the order of hundreds of meters) allowing long‐distance propagation. Third, night and early morning hours are characterized by reduced background atmospheric noise that enhances signal detectability. This work describes the characteristics of the infrasound from a quasi‐continuous source with the potential for long‐range propagation that could be used to monitor the lower part of the atmospheric boundary layer.

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Experimental Identification of Acoustic Emission Characteristics of Large Wind Turbines with Emphasis on Infrasound and Low-Frequency Noise

Cited by 31 publications

References 0 publications

Responses of the ear to low frequency sounds, infrasound and wind turbines

Responses of the ear to low frequency sounds, infrasound and wind turbines

Low-frequency noise from large wind turbines

On infrasound generated by wind farms and its propagation in low‐altitude tropospheric waveguides

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