Experimental studies of the impact of amplitude modulation (AM) and tonality on the annoyance of wind turbine noise in the low frequency (LF) range

Abstract

Amplitude modulation (AM) testing is most often limited to the band from 100 Hz to 800 Hz. The impact of AM and tonality on the annoyance of wind turbine (WT) noise in the frequency range below 100 Hz was undertaken as part of the work. In many works, complaints about the annoyance of WT noise in the low frequency (LF) band are raised, although the energy levels in this band do not exceed the threshold of perception. One of the reasons for such complaints may be AM and tonality. Acoustic signals were recorded in the band from 1 Hz to 20 kHz, at distances from 250 to 1500 m from the turbine at various wind speeds. From the recorded results, samples with the presence of AM and samples with tonal components were selected. The modulation depth, tonality or frequency modulation (FM) were determined for each sample. Preliminary listening tests were also carried out, in which the stimulus was the samples of recordings with AM and tonal components. The listening range was limited to the LF band. Preliminary studies showed no significant differences in noise perception between these samples. Further research is planned with recordings of greater tonality and AM depth.