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01.05 – 30.06.2022 Infrasound research: Pawel Malecki, Tadeusz Wszolek, Malgorzata Pawlaczyk.

Infrasound is low-frequency acoustic waves. By convention, the boundary between the audible and infrasound bands is taken as 20 Hz. These signals are common in the environment, and their sources include modern transportation, extensive ventilation lines, large machinery, wind farms, but also the wind itself or large waterfalls or sea waves. There are many indications of the adverse effects of infrasound on human well-being and health, but due to the technical difficulties involved in recording and, above all, reproducing infrasound in laboratory conditions, research in this area is not very common.

Within the framework of the Hetman project, we are working intensively on this issue. In recent months, we have conducted a series of experiments involving the recording and subsequent controlled exposure of infrasound occurring in the vicinity of wind farms, under laboratory conditions.

For this purpose, we used large-size subwoofer systems used for sounding mass concerts to reconstruct the infrasound band in the 10-20 Hz range.

More than 120 people participated in the study, and exposure to the test signal lasted at least an hour. Preliminary analyses indicate very little annoyance from infrasound generated by wind turbines, confirming the results of similar experiments conducted in other countries.

From June 14-17, our representation of UAM, AkustiX and GIG was in Norway for a study visit with Mr. Truls Gjestland at the SINTEF institute. During the stay, a seminar was held,
at which we were introduced to the principles of SINTEF and also discussed the social aspects of wind turbines. Participants also had the opportunity to analyze in detail the operation of the NORD2000 algorithm used in Norway for wind turbine noise prediction.

The participants visited a wind farm located in the hills near the sea. The farm’s operator talked about the legal aspects of the farms’ operation in Norway and outlined the relationship between the manager and local residents.

The friendly atmosphere throughout the trip allowed both to acquire a lot of new knowledge
as well as establish better relations between the project partners.

We would like to inform you that a series of surveys have been carried out among the residents of the district of Slubice.
For each person, the actual study of the degree of perceived annoyance of the presence of wind turbines, was preceded by a professionally conducted by a qualified person, audiometric hearing test. Those who participated in the Hetman project’s research were thus able to check the state of their hearing, receiving an audiogram along with a discussion of the results obtained. Each person tested also received a small commemorative gift with the logo of the Hetman project.

On 09/07/2021, our team from the University of Science and Technology conducted a study to verify the use of wind shields for measuring low-frequency and infrasound noise. The results of the measurements will be used to develop a method for measuring low-frequency noise and infrasound. The measurements used a multi-channel proprietary measurement system with wireless data transmission, allowing signals to be recorded at several points simultaneously.

On 27.04.2022, as part of the INAD (International Noise Awareness Day) celebrations, organized by the Department of Acoustics of the Faculty of Physics of the Adam Mickiewicz University, Anna Preis gave a remote lecture entitled.
“Can a wind turbine be a good neighbor to humans?”. The lecture was followed by an interesting discussion on the subject of the annoyance of wind turbine noise. As part of the celebration, participants were invited to a sound walk around Poznań and other activities aimed at raising awareness of the quality of the sound environment among the residents of Poznań, as well as remote participants.

On 18.02.2022, our team from the University of Science and Technology conducted measurements of low-frequency noise generated by the main fan station at the mine shaft. The measurements were used to develop a measurement method for low-frequency noise
and infrasound.

The tested source generates noise with similar characteristics to that of wind turbines and can also operate in windless conditions. This makes it possible to record the noise generated by this source without interference from the wind. During the study, signals were recorded
under windless and windy conditions for different wind speeds using different wind shields. The contribution of wind-induced interference to the measurement signals was then determined.