Incidental public exposure to VHF (Very High Frequency) sound and Ultrasound has increased dramatically in recent years due to sources such as the testing of public address systems and pest deterrents. Research into potential health effects and regulation of public exposure has not kept pace with these developments. The majority of the studies used to inform guideline exposure limits focus on occupational exposure, with study subjects limited to relatively small samples of young men.
In practice, the general public consists of people with a wide range of sensitivities to the effect of VHF and ultrasound. Children and young people in particular are known to have greater hearing acuity at high frequency, a fact that has been exploited by the use of Mosquito devices to deter teenagers from congregating in particular areas.
There is very little public awareness of this issue, though the topic has recently received increased media attention, despite measurements being made of ultrasonic tones in public spaces such as railway stations and museums with a footfall of millions of people per year.
Apex is working to raise awareness of these issues and contribute primary data by undertaking surveys of potential sources in schools and public places. You can download our paper from the 2016 Institute of Acoustics conference proceedings here, and read more about the findings of the Health Effects of Ultrasound in Air research group led by Prof Tim Leighton the University of Southampton.
You can read more about our work on this subject in our article for the Journal of the Acoustical Society of America (JASA), the highest profile academic publication for acoustics globally.