Soundscape Analysis and Wildlife Presence in the Vicinity of a Wind Turbine
Wednesday 3 june, 2015, 16:20 - 16:40
0.6 Madrid (49)
The purpose of the present work was to reuse existing acoustic data to evaluate wildlife presence in the vicinity of a wind turbine. The setting is a rural nature park in Chevetogne, Belgium, where a 800 kW, 100 meter high single turbine has been in operation since 2007. Two weeks of 12000 Hz continuous sound data were measured at three positions around the turbine, at distances of 100 and 200 meters. The initial aim of this data was to comment on wind turbine noise. Upon inspection, the audio records were found to contain elements of anthropophony (the turbine, various vehicles, voices), geophony (wind) but most interestingly a rich biophony (birds, insects and mammals). The detected bird species are common in the area. Color-composite spectrograms, assembled from acoustic indicators that target wildlife detection, allow a direct visualization of 24 hours of sound data at once. The acoustic complexity index (ACI) excels at highlighting the contributions of passerines, while a modified spectral entropy (Hs) captures the voices of birds with more monotonous songs. A third dimension, derived from the sound pressure level, gives a sense of the weight of human activities on the soundscape, namely through road traffic. The final spectrograms display the musical composition of the day, showing birds singing on and off in succession or simultaneously but in different frequency ranges. Several variants of turbine noise (nacelle shifts, blade flow noise, whining) are present in the recordings, most clearly at night. None of them appear on the wildlife spectrograms. There is no further evidence of turbine noise interrupting bird communication within the timeframe of the experiment. On the contrary, singing birds were captured by all microphones, indicating territorial behavior also at 100 meters from the turbine. However, the wide range of turbine operating conditions limits potential generalizations of the results.
ICS file for iCal / Outlook