Scheifele, P. M.

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Polarforschung 72 (2/3), 77 - 78, 2002 (erschienen 2004Effeets ofLow-Frequeney Anthropogenie Noise on the81. Lawrenee Beluga Hearing and Communieation Proeesses:a Modelby Peter M. Scheifele'CURRENT DATA FROM THE ST. LAWRENCE RIVERESTUARY AREAThe average source level for whale watehing vessels in theTadoussac, Quebec, Canada area is 151 dB re 1 ,uPa at 1 m.Source levels increase with speed and are audible out to 10 kmfrom two of the three sites monitored. The average time ofcontinuous whale watehing at close range (within 200 m) by atleast three large vessels and up to five small craft and zodiacswas 2.7 hours at the three monitored sites (Tab. 1).determined nor was there good know1edge of the animals'othology and the testing was done in either pool systems orembayments The behaviour of the Beluga varies but in manycases they remain with the larger whales. These behavioursrange from habituation and acclimation (no obvious change ofbehaviour from the "norrn") to flight. The groups traversethese sites routinely each day and mainly remain near thesurface (down to 8 m). They have been seen followingmerchants but rarely whale watchers.Year 1995 Year 2001dB re 1 pPa at 500 Hz7:00 10:00 13:00 16:00 Marginal 7:00 10:00 13:00 16:00 MarginalMean MeanSaguenay 98.0205 106.5074 117.0003 100.5716 105.52495 96.9811 108.002 119.575 120.5996 108.1860333Channel Head 101.2314 120.7552 122.9611 114.5951 114.8857 103.0001 123.9204 125.3961 115.9819 117.4388667Allouette 91.1153 98.9857 98.1111 116.8251 101.5093 925631 120.8144 124 109.7229 112.4558333Year 1995 Year 2001dB re 1 pPa at 1000 Hz7:00 10:00 13:00 16:00 Marginal 7:00 10:00 13:00 16:00 MarginalMean MeanSaguenay 95.7666 102.3036 106.6135 100.5639 101.3119 98.1247 122.1824 139.0200 128.2837 121.9033Channe1 Head 98.6279 99.7716 113.4151 108.2873 105.0255 116.4821 124.5229 125.001 128.5639 123.6425Allouette 82.3825 91.0019 92.3428 95.7212 90.3621 89.4246 97.1932 94.2359 88.8025 91.4141Tab. 1: Comparison of mean noise levels at three sites across four times of day in 1995 and 2001.• Octave band noise (for = 504 and 1,007 Hz) versus audibi-lity,• 15 dB above at 500 Hz,• 22 dB above at 1000 Hz,• Broadband noise,• Dominant tones from below 50 Hz to 1 kHz (exeludingzodiacs).The relationship of the noise to Beluga hearing can be ob-served and we do have hearing threshold curves for theseanimals (Fig. 1). The hearing threshold curves are based onbehavioural, pure tone audiometry using captive animals.There are still issues with this type of hearing testing includ-ing the fact that age in some cases could not be accurately140cu 1200-:l.-e--' 100~co:r:'- 80'0(5J:: 60CI)~J::I- 40200.2 10 100 200Frequency (kHz)Fig. 1: Smoothcd hearing thresho1d curve for the Beluga Whalc Delphinapte-, University of Connecticut, Department of Animal Seience and National Undersea Re- rus leucas. This curve incorporates the data of WHITE et al. (1978) for fre-search Center, 1080 Shennocosset Road, Groton, CT 06340-6048, U.SA quencies from 1 kHz to 120 kHz and SCHEIFELE (1996) from 100 Hz to 1 kHz.77CURRENT METHODS OF NOISE MONITORING ANDANALYSIS• Acoustic Tags; exposure duration, location, noise level- thisyear.• Acoustic Buoys; used with vertical arrays planned.• Articulation Index Methodology; used with vocalizationcIassification for communications interference assessmentbeing tested.Three specific notes of caution regarding monitoring andjudgments on noise impacts on cetacean hearing must beaddressed:(l) Frequencies of the noise relative to the dynamic range ofhearing especially when specifying frequencies of interestsuch as with regard to animal communication and vocaliza-tion 01' echolocation frequencies.(2) Intensity. The decibel is NOT a good unit of measurementwith regard to hearing and noise. Simply making physi-callmathematical conversions between air and water is in er-rar and not satisfactory since it has no relevance to the ear andhearing and assumes that aerial and aquatic ears are equiva-lent. Intensity (Wm2) is a better choice.(3) Duration of exposure is the item that actually forms thebasis of damage risk criteria once the previous two items ofinterest are chosen. Constant exposure to lower intensitysounds can still cause hearing damage in the lang run (refer-ence OSHA Standards for occupational noise exposure andhearing loss).In addition, "acoustic behaviour" is not a good indicator ofhearing damage since:78(l) it cannot be shown with certainty that a behaviour on thepart of an animal in the natural environment is actually thedirect result of an acoustical event;(2) it is Iikely that by the time the behaviour occurs, somehearing damage may have already been done.SUMMARY(l) St. Lawrence River Estuary appears to be an acoustic "hot-spot" in summer.(2) Diving and foraging patterns need to be assessed in thenoise to determine actual long-terrn hearing effects.(3) Mitigation will require behavioural changes on the part ofhumans and can only be based presently on what we know ofhuman and terrestrial animal information and audiology.(4) More information is needed on central auditory processesin marine mammals to fully understand the impacts of noise.(5) Some human audiological and speech science methodsmay prove useful in analyses.(6) Artificial neural networks and information analysis tech-niques may be useful in the near-terrnReferencesScheifele, PM. (1996): Effccts of low-Ircqucncy noise on the hearing of theBeluga Whale (Delphinapterus leucas) of the Saint Lawrence RiverEsruary.- Univ. Connecticut. Report to Parks Canada I GREMM.White, M.J, Norris, J, Ljungblad, D, Baron, K. & Di Sciria, G. (1978):Auditory thresholds of two Beluga Whales (Delphinapterus leucasr-Hubbs Sea World Res. Inst. and Naval Ocean Systems Center, San Diego,Calif. Tech. Rep. H/SWRI 78-109.

Effects of Low-Frequency Anthropogenic Noise on the St. Lawrence Beluga Hearing and Communication Processes: a Model

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