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A Century of Sonar: Planetary Oceanography, Underwater Noise Monitoring, and the Terminology of Underwater Sound
part standard ISO/IEC 80000 ‘Quantities and Units’ (Jensen and Thor, 1995; IEC, 2012). This joint ISO/IEC Standard describes the International System of Units (SI), other stan- dardized units intended for use alongside the SI such as the decibel and the neper, and the corresponding system of quantities, known as the International System of Quantities (ISQ) (BIPM, 2006).
In 2011, an ISO technical sub-committee (ISO/TC 43/SC 3) dedicated exclusively to underwater acoustics was estab- lished (ISO, 2012). The need for an unambiguous under- water acoustics terminology was identified in June 2012, at the inaugural meeting of that sub-committee. The new standard ISO 18405 Underwater Acoustics - Terminology, under development by ISO Working Group ISO/TC 43/SC 3/WG 2, is based on Parts 3 and 8 of ISO/IEC 80000, and is scheduled for publication as an International Standard in 2016. This new standard will include definitions, reached by international consensus, not only of basic terminology al- ready mentioned (“sound pressure,” “sound pressure level,” “sound exposure”), but also of more advanced terminology such as “source level” (a measure of source power,) “tempo- rary hearing threshold shift” (a measure of change in hear- ing sensitivity,) and “detection threshold” (a measure of the minimum signal-to-noise ratio required for a sonar to cor- rectly identify a signal in the presence of noise.)
A Parting Plea
Underwater acousticians, myself included, have a responsi- bility to provide a clear, concise, and unambiguous language with which to communicate results and ideas about our sci- ence. The sooner we provide that language, the sooner in- dustry, governments, and scientists will start to benefit from its use. We must not let them wait a minute longer than is necessary.
Acknowledgments
I thank Timothy Leighton and Arthur Popper for detailed reviews, Steve Vance for tips on planetary acoustics, and Mi- chele Halvorsen, Amy Scholik-Schlomer, and René Dekeling for helpful comments.
Biosketch
Michael Ainslie is a Senior Scientist at TNO (Nether- lands) and Visiting Professor at the Institute of Sound and Vibration Research, Univer- sity of Southampton (UK). He holds degrees in physics (Imperial College, 1981) and mathematics (University of Cambridge, 2011), and a PhD in seabed acoustics (University of Southampton, 1991). He is author of the
book Principles of Sonar Performance Modeling (Springer, 2010), and his research interests include sonar performance modeling and effects of sound on aquatic life. He is Con- venor of the ISO Working Group ISO/TC 43/SC 3/WG 2 (Underwater Acoustical Terminology), and a member of the ANSI Working Group ANSI/S 3/WG73 (Bioacoustical Ter- minology).
References
Ainslie, M. A., and Morfey, C. L. (2005). “’Transmission loss’ and ‘propaga- tion loss’ in undersea acoustics.” Journal of the Acoustical Society of Amer- ica, 118(2), 603-604.
Ainslie, M. A. (2008). “The sonar equations: Definitions and units of indi- vidual terms.” Acoustics 08, Paris, June 29–July, 4, 30.
ANSI (1960). ANSI S1.1-1960 (R1976) “Acoustical Terminology” (Ameri- can National Standards Institute, New York).
ANSI (1969). ANSI S1.8-1969 (R1974) “Preferred Reference Quanti- ties for Acoustical Levels” (American National Standards Institute, New York).
ANSI (1989). ANSI S1.8-1989 “Reference Quantities for Acoustical Levels” (American National Standards Institute, New York).
ANSI (2013). ANSI S1.1-2013 “Acoustical Terminology” (American Na- tional Standards Institute, New York).
Arvelo, J., and Lorenz, R. (2013). “Plumbing the depths of Ligeia: Consid- erations for depth sounding in Titan’s hydrocarbon seas,” Journal of the Acoustical Society of America 134, 4335-4350 (2013).
ASA(1951).ASAZ24.1-1951(RevisionofZ24.1-1942)“AmericanStandard Acoustical Terminology” (American National Standards Institute, New York). Available from https://archive.org/stream/ameri00amer#page/n1/ mode/2up, last accessed 9 August 2014.
Beaudoin, J., Sade, A., Schulze, B., and Hall, J. K. (2014). “Dead Sea Multi- beam Echo Sounder Survey: Severe Refraction Issues at 1,840 m/s Sound Speeds, 20% Above Normal,” available from http://www.hydro-interna- tional.com/issues/articles/id1307-Dead_Sea_Multibeam_Echo_Sound- er_Survey.html, last accessed 21 August 2014.
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