Infrasound
Infrasound
Wind turbines also produce infrasound. Infrasound is a sound with a frequency (Hz) of less than 20 Hz. Depending on its strength, infrasound can be either audible or remain below the lower limit of audibility. In most cases, however, we do not hear the infrasound in our environment.
Infrasound that is below the lower limit of audibility, i.e. inaudible, is present everywhere in our environment. It is generated, for example, from atmospheric pressure variations, wind, vibrations of structures, swinging or, for example, running steps on a certain type of base. Infrasound below the lower limit of audibility is also generated in various industrial processes, such as wind turbines. According to studies, the infrasound pressure level of wind turbines remains significantly below the lower limit of audibility.
Study on infrasound
Infrasound is subject to the same laws as any other sound, and its potential health impacts are also generated in the same situations as other kind of sound. According to a scientific study, it has not been proved that infrasound has any health impacts as long as it is inaudible. (e.g.. Hongisto & Oliva 2017.)
In Finland, the health impacts of infrasound generated by wind power have been examined in several studies, e.g. in a government-funded project (2020), in which the impact of infrasound was studied extensively with long-term sound measurements, questionnaires conducted in wind power areas, and listening and physiological tests.
According to the results of listening tests carried out in a laboratory, the test persons were unable to detect infrasound in the sound samples, and infrasound had no impact on the perceived annoyance of the sound. Moreover, no difference in stress indicators between different groups or sound samples were found in the physiological measurements. Although some of the nearest residents of the wind power areas stated in the questionnaire that their symptoms were connected to the wind turbines, the results of the survey do not support claims that the infrasound of wind power would cause a health hazard.
According to research results, symptoms related to wind turbines are therefore not explained by the infrasound of wind turbines. The results show that symptoms can be explained by the fact that wind turbines are perceived to be annoying and that they are regarded as a health risk. It is also possible that symptoms and illnesses that are unrelated to the infrasound of wind turbines are interpreted to be caused by them. The interpretations are also affected by the ongoing public debate.
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