Sounds in the laboratory and animal house environment were monitored for sound pressure levels over both low frequency (10Hz-l2.5kHz) and high frequency (12.5—70 kHz) ranges and were recorded for frequency analysis over the range 10Hz-100kHz. Forty sources of sound were investigated at 10 different sites. Sources included environmental control systems, maintenance and husbandry procedures, cleaning equipment and other equipment used near animals. Many of the sounds covered a wide frequency band and extended into the ultrasonic (> 20kHz) range. Sound levels produced by environmental control systems were generally at a low level. High sound pressure levels (SPLs) up to and exceeding 85dB SPL were recorded during cleaning and particularly high levels were recorded from the transport systems studied. Equipment such as a tattoo gun, a condensation extractor system, a high-speed centrifuge, and an ultrasonic disintegrator produced high levels of sound over a broad spectrum.

As many laboratory animals are much more sensitive to a wider range of sound frequency than humans, it seems likely that the levels of sound reported here could adversely affect animals through physiological or behavioural changes, or may even cause sensory damage in extreme cases. There appear to have been no studies on the minimal threshold levels for such adverse responses, or on the long-term effects of exposure to the types of sounds recorded here. It is not yet possible to set realistic exposure limits for laboratory animals.