Strategies for weighting exposure in the development of acoustic criteria for marine mammals by the Noise Exposure Criteria Group Presented to the 150th Meeting of the Acoustical Society of America 17–21 October 2005, Minneapolis, MN

Noise Exposure Criteria Group (Authors) Ann Bowles Roger Gentry William Ellison James Finneran Charles Greene David Kastak Darlene Ketten James Miller Paul Nachtigall W. John Richardson Brandon Southall* Jeanette Thomas Peter Tyack Former Contributors Whitlow Au Sam Ridgway* (ret) Ron Schusterman (ret) *Note that Brandon Southall was left off the author list in the program. An erratum will be published in the Journal and author list will be corrected online.

NMFS Charge to the Noise Exposure Criteria Group Develop science-based criteria for the onset of auditory injury and behavioral disruption from noise exposure. It became clear that we needed to emphasize some frequencies and deemphasize others It would be best if each species had their own weighting functions for injury and behavior. But we don’t have the data to support the specification of these weighting functions. While these data are being collected, we need interim weighting functions.

Marine Mammal Groups: Taxa were categorized into groups by hearing function Composite data (see: Richardson et al., 1995; Kastelein et al., 2002)

Human Hearing: Weighting Functions Nominal Range of Human Hearing 20 Hz – 20 kHz (source: Harris 1998) In humans, an idealized version of the 40-phon equal loudness function (A-weighting) and 100-phon equal loudness function (C-weighting) are used to filter sound when calculating estimates of exposure.

Leatherwood, J.D., B.M. Sullivan, K.P. Shepherd, D.A. McCurdy, and S.A. Brown Summary of recent NASA studies of human response to sonic boom. Journal of the Acoustical Society of America 111(1, pt. 2): 566–598. Frequency weighting improves correlation between noise exposure and human response Log measure of annoyance

Example of sound exposure relative to human hearing and frequency weighting (arb. dB) A-weighting (inverted) A- and C-weighting admit different portions of the sonic boom spectrum (in arb. dB). These weighting functions admit more low frequency noise than the human auditory threshold function.

Example of noise exposure* relative to marine mammal hearing Pinniped threshold data from: Kastak, D. and R.J. Schusterman Low-frequency amphibious hearing in pinnipeds: methods, measurements, noise and ecology. Journal of the Acoustical Society of America 103(4): 2216 – California Sea LionHarbor SealNorthern Elephant Seal *Sonic boom spectrum (arb. dB)

Human Frequency Weighting Networks H. Singleton, “Frequency Weighting Equations,” (2004).

Weighting Functions for Animals Weightings should improve exposure estimates i.e., reduce the variability of correlations between dose and response Ad hoc weightings have been used historically Human A- and C-weightings (whether or not they match the animals’ hearing range) Species-typical auditory threshold functions ( “O-weighting” for owls [ Delaney et al ], “R-weighting” for laboratory rats [NIH]). “Flat” weighting o Rectangular weighting constrained by the upper and lower boundaries of the measurement system. Rectangular weighting constrained by the upper and low boundaries of the animal’s hearing range. The 1/3-octave band with the greatest energy

Threshold Weighting The absolute auditory threshold function (audiogram) has been suggested as a surrogate weighting function for marine species exposed to underwater sound (Malme 1990; Heathershaw et al. 2001; Nedwell and Edwards, 2002; Nedwell et al, 2005) as well as terrestrial animals (Delaney et al. 1999; Bjork et al. 2000) The absolute auditory threshold function (audiogram) has been suggested as a surrogate weighting function for marine species exposed to underwater sound (Malme 1990; Heathershaw et al. 2001; Nedwell and Edwards, 2002; Nedwell et al, 2005) as well as terrestrial animals (Delaney et al. 1999; Bjork et al. 2000) The utility of this approach has not been tested empirically. The utility of this approach has not been tested empirically.

Weighting Functions for Marine Mammals S3 WG90 is developing recommendations for marine mammal weighting functions, but adequate science is needed to produce standardized, taxon-specific weightings In the interim, a simple, conservative weighting scheme was developed for marine mammals

M-Weighting Species Group f low f high Low-frequency cetaceans 7 Hz 22 kHz Mid-frequency cetaceans 150 Hz 160 kHz High-frequency cetaceans 200 Hz 180 kHz Pinnipeds in water 75 Hz 75 kHz Pinnipeds in air 75 Hz 30 kHz The frequency cutoffs can be obtained from anatomical studies. The numbers here are conservative estimate of the upper and lower boundaries for the most sensitive members of each group.

Functional Hearing Group Estimated Auditory Bandwidth Genera Represented (# species/sub-spec.) Frequency Weighting Network Low-frequency cetaceans 7 Hz to 22 kHz Balaena, Caperea, Eschrichtius, Megaptera, Balaenoptera (13 species/sub-spec.) M lf (lf: low-frequency cetacean) Mid-frequency cetaceans 150 Hz to 160 kHz Steno, Sousa, Sotalia, Tursiops, Stenella, Delphinus, Lagenodelphis, Lagenorhynchus, Lissodelphis, Grampus, Peponocephala, Feresa, Pseudorca, Orcinus, Globicephala, Orcacella, Physeter, Kogia, Delphinapterus, Monodon, Ziphius, Berardius, Tasmacetus, Hyperoodon, Mesoplodon (56 species/sub-spec.) M mf (mf: mid-frequency cetaceans) High-frequency cetaceans 200 Hz to 180 kHz Phocoena, Neophocaena, Phocoenoides, Platanista, Inia, Lipotes, Pontoporia, Cephalorhynchus (18 species/sub-spec.) M hf (hf: high-frequency cetaceans) Pinnipeds in water 75 Hz to 75 kHz Arctocephalus, Callorhinus, Zalophus, Eumetopias, Neophoca, Phocarctos, Otaria, Erignathus, Phoca, Pusa, Halichoerus, Histriophoca, Pagophilus, Cystophora, Monachus, Mirounga, Leptonychotes, Ommatophoca, Lobodon, Hydrurga, and Odobenus (41 species/sub-spec.) M pw (pw: pinnipeds in water) Pinnipeds in air 75 Hz to 30 kHz Same genera as pinnipeds in water (41 species/sub-spec.) M pa (pa: pinnipeds in air) These groups are relatively heterogeneous – it was the breakdown that is supported with available data.

“M-weighting” for cetacean hearing Low-frequency cetaceans - f low : 7 Hz, f high : 22 kHz Mid-frequency cetaceans - f low : 150 Hz, f high : 160 kHz High-frequency cetaceans - f low : 200 Hz, f high : 180 kHz The resulting family of weighting functions should yield metrics that are most relevant for high-amplitude noise exposures (where loudness functions are expected to flatten) and are likely conservative.

“M-weighting” for pinniped hearing Note that we are not taking into account the differences in best sensitivity among species.

Conclusions The Noise Exposure Criteria Group has developed weighting procedures for exposure metrics that will be used as criteria for The Noise Exposure Criteria Group has developed weighting procedures for exposure metrics that will be used as criteria for injury injury behavioral disruption behavioral disruption Noise exposure metrics for humans have proven to be more effective when they account for psychophysical properties of the auditory system, particularly loudness perception. Noise exposure metrics for humans have proven to be more effective when they account for psychophysical properties of the auditory system, particularly loudness perception. The Group has proposed to weight noise data by functions that admit sound throughout the frequency range of hearing in five marine mammal groupings. The Group has proposed to weight noise data by functions that admit sound throughout the frequency range of hearing in five marine mammal groupings. This procedure is considered conservative This procedure is considered conservative The “precautionary principle” is always used in developing criteria for species at risk. The “precautionary principle” is always used in developing criteria for species at risk. Empirical data are essential to finding better estimators of exposure including refining the cutoff frequencies for the weightings. Empirical data are essential to finding better estimators of exposure including refining the cutoff frequencies for the weightings.

References Bjork, E., T. Nevalainen, M. Hakumaki, and H.-M. Voipio. (2000). R-weighting provides better estimation for rat hearing sensitivity. Lab. Anim. 34,136–144. Bjork, E., T. Nevalainen, M. Hakumaki, and H.-M. Voipio. (2000). R-weighting provides better estimation for rat hearing sensitivity. Lab. Anim. 34,136–144. C. M. Harris, Handbook of Acoustical Measurements and Noise Control, 3 rd ed., Acoustical Society of America, C. M. Harris, Handbook of Acoustical Measurements and Noise Control, 3 rd ed., Acoustical Society of America, R. A. Kastelein, P. Bunskoek, M. Hagedoorn, W. W. L. Au, and D. de Haan, “Audiogram of a harbor porpoise (Phocoena phocoena) measured with narrow-band frequency-modulated signals,” J. Acoust. Soc. Am., 112(1), , R. A. Kastelein, P. Bunskoek, M. Hagedoorn, W. W. L. Au, and D. de Haan, “Audiogram of a harbor porpoise (Phocoena phocoena) measured with narrow-band frequency-modulated signals,” J. Acoust. Soc. Am., 112(1), , D. Kastak and R.J. Schusterman, Low-frequency amphibious hearing in pinnipeds: methods, measurements, noise and ecology, J. Acoust. Soc. Am., 103(4), 2216 – 2228, Heathershaw, A.D., P.D. Ward and A.M. David The environmental impact of underwater sound. p In: 2nd Symp. on underwater bio-sonar and bioacoustic systems, Loughborough Univ., July Proc. Inst. Acoustics 23(4). Inst. of Acoustics, St Albans, Herts, U.K. 202 p. J. Acoust. Soc. Am., J. D. Leatherwood, B.M. Sullivan, K.P. Shepherd, D.A. McCurdy, and S.A. Brown, “Summary of recent NASA studies of human response to sonic boom,” J. Acoust. Soc. Am., 111(1, pt. 2), 566–598, J. Nedwell, B. Edwards, 'Measurements of underwater noise in the Arun River during piling at County Wharf, Littlehampton', Subacoustech Report Reference: 513R0108, August J. Nedwell, B. Edwards, 'Measurements of underwater noise in the Arun River during piling at County Wharf, Littlehampton', Subacoustech Report Reference: 513R0108, August J. Nedwell, J. Lovell, A. Turnpenny, “Experimental validation of a species-specific behavioral impact metric for underwater noise,” J. Acoust. Soc. Am., 118(3), J. Nedwell, J. Lovell, A. Turnpenny, “Experimental validation of a species-specific behavioral impact metric for underwater noise,” J. Acoust. Soc. Am., 118(3), W. J. Richardson, Jr., C. R. Greene, C. I. Malme, D. H. Thomson, Marine Mammals and Noise, Academic Press, W. J. Richardson, Jr., C. R. Greene, C. I. Malme, D. H. Thomson, Marine Mammals and Noise, Academic Press, H. Singleton, “Frequency Weighting Equations,” (2004). H. Singleton, “Frequency Weighting Equations,” (2004).

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