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Analysis of aerodynamic sound noise generated by a large-scaled wind turbine and its physiological evaluation
Inagaki, T.; Li, Y. & Nishi, Y.
Abstract
Aerodynamic noise generated from a modern
large-scale wind turbine was measured and analyzed from
an engineering point of view. The measurement items were
the sound, the sound pressure level (including the infrasound
with extremely low-frequency band) and the corresponding
physiological evaluation. Fifteen test subjects
received various sound stimuli, including the recorded
aerodynamic noise and a synthetic periodical sound, were
examined with an electroencephalogram as a physiological
evaluation. It was observed from the mapping patterns of
brain waves that alpha1 rhythm, which indicates a relaxed
and concentrated state, after the sound stimulus with the
frequency band of 20 Hz, showed the lowest value among
the other cases. That is, the test subjects cannot keep
relaxed and their concentration after hearing the sound
stimulus at the frequency band of 20 Hz. The induced rate
of alpha1 rhythm almost decreased when the test subjects
listened to all the sound stimuli, and further decreased with
decreased frequency. Meanwhile, beta1 rhythm, which
shows a strain state, after the sound stimulus with the
frequency band of 20 Hz, showed the highest value among
the other cases. Therefore, the infrasound (e.g., low frequency
and inaudible for human hearing) was considered
to be an annoyance to the technicians who work in close
proximity to a modern large-scale wind turbine.
Keywords
Infrasound noise; Aerodynamic noise; Wind turbine; Environmental impact assessment; Electroencephalogram; Physiological evaluation
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