This report presents results of the noise monitoring program performed at 6 sites in the vicinity to Waterloo Wind Farm over approximately two months, at distances ranging between 1.3 and 7.6 km, covering a broad range of directions.
Measurements of noise inside and outside of houses were undertaken at 5 sites.
No evidence was found for the presence of excessive infrasound within the infrasound frequency range. The blade pass frequency component, which falls within the infrasound frequency range, was found to be below the perception threshold by a significant margin, and typical levels were consistent with results of other relevant studies. G-weighted levels were also found to be below the perception threshold.
Wind farm noise was found to be audible at very low levels at the other sites, with a slight degree of modulation; but rarely dominated the noise environment during the monitoring period. Where it could be identified, wind farm noise was generally only discernible with substantial amplification of audio records. A ‘rumbling’ character could be identified in amplified audio records at three residences (North East, West and South East sites), typically under downwind conditions.
The data showed that operation of the wind farm may have contributed to the low frequency content of noise under some operating and environmental conditions during the period, resulting in increases of relevant low frequency noise descriptors. As with the rumbling effect, the low frequency content was not discernible subjectively when replaying audio records at actual levels, but could be detected with amplification.
Analysis of data for the sites showed that high level of low frequency noise is typical for some of the sites, most likely due to natural background or ambient noise sources, for which low frequency descriptors were found to be comparable with those from the wind farm, or at times even higher.
The noise diaries were essential to the study in focusing the acoustic analyses on events and descriptions recorded by the community. In particular, the identification of the rumbling effect and other noise characters associated with the wind farms was facilitated by diary returns. However, it is noted that in analysing audio records acquired during the study, amplification was generally necessary to hear these effects.
Nevertheless, it is possible that people who have a higher sensitivity to the lower frequencies in particular may detect these characteristics, and they may cause increased annoyance for those who have been aware of them for a prolonged period.
Noise impact from the wind farm, where detectable, was found to comply with the conditions of the development approval and the baseline criterion of 40dB(A).