80 dB at 1 kHz, decreasing to a minimum of ~60 dB around
20,000 Hz, and then increasing to higher sound pressure
levels as the frequency increases. This NTE curve tracks
the hearing threshold for rats, basically adding 60 dB to the
hearing threshold. The MD Anderson report stops short of
recommending these criteria, but they offer an excellent
starting point for the discussion.
Clearly the most effective way to assure the health and safety of
laboratory animals as this relates to ultrasound is to specify measurements prior to turning over the lab. The measurements should
include the locations as recommended by MD Anderson, but in
addition, a measurement survey should be conducted of laboratory equipment and MEP, to be put in use throughout the facility.
Reporting the ultrasonic levels produced by specific equipment
would also be useful. Perhaps a database of such measurements
could be established so designers can readily specify equipment
meeting the needs of animal laboratories. If such a database were
to be established, manufacturers might be encouraged to provide
data for their own products. The benefits of such a system would
be greater economy, enhanced animal well-being, and greater
control of variables in the research protocol.
1. Specialized instrumentation is required to measure ultrasound. The
very high frequencies necessitate the use of specialized 1/4” microphones and high speed data acquisition systems capable of sampling
at 200 kHz.
2. kHz means thousand Hz, so 20 kHz = 20,000 Hz. Likewise MHz
means million Hz
3. Sound Pressure Level in decibels relative to 20 micro-Pascals.
4. Kelly JB & Masterton B (1977) Auditory sensitivity of the albino rat.
Journal of Comparative and Physiological Psychology 91, 930-936
5. Ehret G (1976) Development of absolute auditory thresholds in the
mouse Mus musculus. Journal of the American Audiology Society 1,
6. Faith, R. and Miller, S. , ALN, 2007-07-01, "The Need for Sound and
Vibration Standards in U.S. Research Animal Rooms"
7. M. J. Castelhano-Carlos and V. Baumans, Laboratory Animals, 2009,
8. pg. 142, Guide for the Care and Use of Laboratory Animals; Eighth
Edition, Committee for the Update of the Guide for the Care and Use
of Laboratory Animals; National Research Council
9. MD. Anderson Noise, Vibration and Ultrasonic Design Guide, is
located on MD Anderson's Owner's Design Guidelines - Supplemental
Dr. Gladys Unger, a Senior Consultant at Acentech, has a wide
range of experience in acoustics and vibration. She has been
involved in remote monitoring of vibration and noise as it
pertains to sensitive research equipment and animal facilities.
33 Moulton St, Cambridge, MA 02138, 617-499-8087, gunger@
Want to read more about noise and vibration concerns
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