Media mislead public about deafness risk of wind turbines
When talking about the volume of sounds people can often be surprised at how loud everyday things are. People with extremely good hearing can hear sounds as quiet as -15dB where the normal hearing threshold is usually around 0dB. Rustling leaves register at about 20dB, the average computer emits approximately 40dB and a normal conversation is typically 60dB. When riding a motorcycle you can be exposed to sounds at 100dB whilst a jet engine taking off is measure at 140dB. Regular, prolonged exposure to these sounds and other sounds of 90dB or more could cause permanent hearing loss. This is why people who have used noisy tools or machines for much of their working life or regularly attended music concerts may suffer with hearing problems.
There has been a wealth of research into the effects of loud noise and much less is known about the effect of lower noises. However, researchers at the University of Munich have been looking at the impact of low-frequency sounds on the inner ear. The research involved 21 young adults with normal hearing who were exposed to a low-frequency pulse sound at 80dB for 90 seconds. After the exposure the researchers recorded faint noises which are naturally emitted from the inner ear, these are a normal occurrence in the ear but have been found to disappear in people suffering with hearing loss.
The research found that there were changes in the faint noises emitted by the ear for approximately two minutes after the participants had been exposed to the low-frequency pulse sound.
Dr Markus Drexl who lead the research explains what the results could mean; “These changes are definitely not normal and we don’t know what happens during longer exposures. You can at least speculate this might be a first indication of the start of a damaging process.”
The report was published alongside a press summary which cited wind turbines as a source of low frequency noise and a number of newspapers latched onto this advising people that living close to a wind farm could damage hearing. Dr Drexl was quick to clarify the issue, saying that such a claim cannot be substantiated by the research as “we haven’t shown whether low frequency sound is causing any damage to the inner ear. I also don’t know of any cases of deafness being reported by people living near wind turbines.”
In fact, the research did not test whether the low-frequency pulse that participants were exposed to caused hearing damage, the only measurement was the noises emitted from the ear which does not necessarily mean that damage has been caused. There is also no evidence that prolonged exposure to these noises causes permanent damage as the study only exposed the participants to the noise for 90 seconds.
In short, the study showed that exposure to low-frequency sounds causes changes in the inner ear however this does not mean that noise from wind turbines causes hearing loss. Further research is required to establish whether the changes in the inner ear are a sign of damage to the ear and whether prolonged exposure to low-frequency sounds causes permanent hearing loss.