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ISVR Consulting are able to measure sound pressure levels at ultrasonic frequencies, i.e. frequencies above the normal audible range. Examples of projects have included
Measurement of the frequency responses of an ultrasonic transmitter and an ultrasonic receiver
Measurements of the output sound level, output frequencies and directionality of an ultrasonic deterrent designed to keep cats out of gardens
Measurements of the output levels of specialist distance measuring devices
Measurements of ultrasonic levels from laboratory equipment and comparison with health and safety guidelines for the operators
Measurements of ultrasound levels from large industrial processors designed to break rock and solids in water down into gravel and sand
Measurements can be made in our anechoic chamber under well-controlled conditions, or on-site if the source of the ultrasound is a large item of plant or part of a large installation.
In exposed individuals, ultrasound can cause unpleasant feelings, including temporary nausea, at levels below those dangerous to hearing. When ultrasonic equipment is used in the workplace we can assess the measured sound levels against guideline limits, to ensure the comfort and well being of those working nearby, as well as their safety.
In 2001 we completed a literature review entitled Â“Damage to human hearing by airborne sound of very high frequency or ultrasonic frequencyÂ” for the Health & Safety Executive. This report, HSE CCR 343/2001 is still relevant and available in Acrobat (pdf) format from the HSE website. A more recent summary is available in Â“Exposure limits for airborne sound of very high frequency and ultrasonic frequencyÂ” by B.W. Lawton, ISVR Technical Report No: 334, April 2013. (pdf 120 KB)
You have the first report, HSE CCR 343/2001, on the pieptonon.nl site. It mentions animal deterrents.
But you might not have read the second document,
Â“Exposure limits for airborne sound of very high frequency and ultrasonic frequencyÂ”, by the same author, Dr Ben Lawton. It is worth reading. In this, he says
This document again summarises the effects reported on individuals from very high frequency/ultrasonic noise.
Note this section
5. THE INFLUENCE OF DURATION
"It is also worth asking: is the incidence of unpleasant subjective effects related solely to the
level of a VHF sound, or does duration play a part? In addition to its occupational aspects,
this question also has significance when considering ultrasonic vermin-repellers, intruder
alarms, and VHF devices intended to disperse unwanted gatherings outside commercial
premises. One may justifiably wonder if subjective effects would appear in susceptible
individuals after only a few minutes of a VHF noise at a level deemed Â“safeÂ” according to the
equal energy concept. "
vermin = pest (unwanted animal)
VHF devices intended to disperse unwanted gatherings outside commercial premises = "Mosquito" or a cat deterrent used to get rid of young people.
Here are the document details:
UNIVERSITY OF SOUTHAMPTON
INSTITUTE OF SOUND AND VIBRATION RESEACH
Exposure limits for airborne sound of very high frequency and ultrasonic frequency
B.W. Lawton , Associate Principal Consultant
April 2013 can be found at