Harderwijk, Netherlands
Harderwijk, Netherlands

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Kastelein R.A.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO | De Jong C.A.F.,TNO | Wensveen P.J.,Andrews University
Journal of the Acoustical Society of America | Year: 2010

The underwater hearing sensitivity of a young male harbor porpoise for tonal signals of various signal durations was quantified by using a behavioral psychophysical technique. The animal was trained to respond only when it detected an acoustic signal. Fifty percent detection thresholds were obtained for tonal signals (15 frequencies between 0.25-160 kHz, durations 0.5-5000 ms depending on the frequency; 134 frequency-duration combinations in total). Detection thresholds were quantified by varying signal amplitude by the 1-up 1-down staircase method. The hearing thresholds increased when the signal duration fell below the time constant of integration. The time constants, derived from an exponential model of integration [Plomp and Bouman, J. Acoust. Soc. Am. 31, 749-758 (1959)], varied from 629 ms at 2 kHz to 39 ms at 64 kHz. The integration times of the porpoises were similar to those of other mammals including humans, even though the porpoise is a marine mammal and a hearing specialist. The results enable more accurate estimations of the distances at which porpoises can detect short-duration environmental tonal signals. The audiogram thresholds presented by Kastelein [J. Acoust. Soc. Am. 112, 334-344 (2002)], after correction for the frequency bandwidth of the FM signals, are similar to the results of the present study for signals of 1500 ms duration. Harbor porpoise hearing is more sensitive between 2 and 10 kHz, and less sensitive above 10 kHz, than formerly believed. © 2010 Acoustical Society of America.


Kastelein R.A.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO | De Jong C.A.F.,TNO
Journal of the Acoustical Society of America | Year: 2011

The distance at which active naval sonar signals can be heard by harbor porpoises depends, among other factors, on the hearing thresholds of the species for those signals. Therefore the hearing sensitivity of a harbor porpoise was determined for 1 s up-sweep and down-sweep signals, mimicking mid-frequency and low-frequency active sonar sweeps (MFAS, 6-7 kHz band; LFAS, 1-2 kHz band). The 1-2 kHz sweeps were also tested with harmonics, as sonars sometimes produce these as byproducts of the fundamental signal. The hearing thresholds for up-sweeps and down-sweeps within each sweep pair were similar. The 50% detection threshold sound pressure levels (broadband, averaged over the signal duration) of the 1-2 kHz and 6-7 kHz sweeps were 75 and 67 dB re 1 μPa 2, respectively. Harmonic deformation of the 1-2 kHz sweeps reduced the threshold to 59 dB re 1 μPa 2. This study shows that the presence of harmonics in sonar signals can increase the detectability of a signal by harbor porpoises, and that tonal audiograms may not accurately predict the audibility of sweeps. LFAS systems, when designed to produce signals without harmonics, can operate at higher source levels than MFAS systems, at similar audibility distances for porpoises. © 2011 Acoustical Society of America.


Kastelein R.A.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO | De Jong C.A.F.,TNO
Journal of the Acoustical Society of America | Year: 2011

Helicopter long range active sonar (HELRAS), a dipping sonar system used by lowering transducer and receiver arrays into water from helicopters, produces signals within the functional hearing range of many marine animals, including the harbor porpoise. The distance at which the signals can be heard is unknown, and depends, among other factors, on the hearing sensitivity of the species to these particular signals. Therefore, the hearing thresholds of a harbor porpoise for HELRAS signals were quantified by means of a psychophysical technique. Detection thresholds were obtained for five 1.25 s simulated HELRAS signals, varying in their harmonic content and amplitude envelopes. The 50 hearing thresholds for the different signals were similar: 76 dB re 1 μPa (broadband sound pressure level, averaged over the signal duration). The detection thresholds were similar to those found in the same porpoise for tonal signals in the 1-2 kHz range measured in a previous study. Harmonic distortion, which occurred in three of the five signals, had little influence on their audibility. The results of this study, combined with information on the source level of the signal, the propagation conditions and ambient noise levels, allow the calculation of accurate estimates of the distances at which porpoises can detect HELRAS signals. © 2011 Acoustical Society of America.


Kastelein R.A.,Sea Mammal Research Company SEAMARCO | Gransier R.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO
Journal of the Acoustical Society of America | Year: 2013

Anthropogenic noise may cause temporary hearing threshold shifts (TTSs) in marine mammals. Tests with identical methods show that harbor porpoises are more susceptible to TTS induced by octave-band white noise (OBN) centered around 4 kHz than harbor seals, although their unmasked (basic) hearing thresholds for that frequency are similar. A harbor seal was exposed for 1 h to an OBN with a very high sound pressure level (SPL), 22-30 dB above levels causing TTS onset. This elicited 44 dB TTS; hearing recovered within 4 days. Thus, for this signal and this single exposure, permanent threshold shift requires levels at least 22 dB above TTS onset levels. The severe TTS in the seal suggests that the critical level (above which TTS increases rapidly with increasing SPL) is between 150 and 160 dB re 1 μPa for a 60 min exposure to OBN centered at 4 kHz. In guidelines on TTS in marine mammals produced by policy makers in many countries, TTS is assumed to follow the equal energy hypothesis, so that when the sound exposure levels of fatiguing sounds are equal, the same TTS is predicted to be induced. However, like previous studies, the present study calls this model into question. © 2013 Acoustical Society of America.


Kastelein R.A.,Sea Mammal Research Company SEAMARCO | Gransier R.,Sea Mammal Research Company SEAMARCO | Gransier R.,Catholic University of Leuven | Marijt M.A.T.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO
Journal of the Acoustical Society of America | Year: 2015

Harbor porpoises may suffer hearing loss when exposed to intense sounds. After exposure to playbacks of broadband pile driving sounds for 60 min, the temporary hearing threshold shift (TTS) of a porpoise was quantified at 0.5, 1, 2, 4, 8, 16, 32, 63, and 125 kHz with a psychoacoustic technique. Details of the pile driving sounds were as follows: pulse duration 124 ms, rate 2760 strikes/h, inter-pulse interval 1.3 s, average received single strike unweighted sound exposure level (SEL) 146 dB re 1 μPa2 s (cumulative SEL: 180 dB re 1 μPa2 s). Statistically significant TTS only occurred at 4 and 8 kHz; mean TTS (1-4 min. after sound exposure stopped) was 2.3 dB at 4 kHz, and 3.6 dB at 8 kHz; recovery occurred within 48 min. This study shows that exposure to multiple impulsive sounds with most of their energy in the low frequencies can cause reduced hearing at higher frequencies in harbor porpoises. The porpoise's hearing threshold for the frequency in the range of its echolocation signals was not affected by the pile driving playback sounds. © 2015 Acoustical Society of America.


Kastelein R.A.,Sea Mammal Research Company SEAMARCO | Gransier R.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO | Rambags M.,Sea Mammal Research Company SEAMARCO
Journal of the Acoustical Society of America | Year: 2013

Harbor porpoises may suffer hearing loss when exposed to intense sounds. After exposure to a 1.5 kHz continuous tone without harmonics at a mean received sound pressure level of 154 dB re 1 μPa for 60 min (cumulative sound exposure level: 190 dB re 1 μPa2 s), the temporary hearing threshold shift (TTS) of a porpoise was quantified at 1.5, 2, 4, 6.5, 8, 16, 32, 63, and 125 kHz with a psychoacoustic technique. Significant TTS only occurred at 1.5 and 2 kHz. Mean TTS (1-4 min after sound exposure stopped) was ∼14 dB at 1.5 kHz and ∼11 dB at 2 kHz, and recovery occurred within 96 min. Control hearing tests before and after a 60 min low ambient noise exposure showed that normal variation in TTS was limited (standard deviation: ±1.0 dB). Ecological effects of TTS depend not only on the magnitude of the TTS, its duration (depending on the exposure duration), and the recovery time after the exposure stopped, but also on the hearing frequency affected by the fatiguing noise. The hearing thresholds of harbor porpoises for the frequencies of their echolocation signals are not affected by intense low frequency sounds, therefore these sounds are unlikely to affect foraging efficiency. © 2013 Acoustical Society of America.


Wensveen P.J.,University of St. Andrews | Huijser L.A.E.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO | Kastelein R.A.,Sea Mammal Research Company SEAMARCO
Journal of Experimental Biology | Year: 2014

Loudness perception by human infants and animals can be studied under the assumption that sounds of equal loudness elicit equal reaction times (RTs). Simple RTs of a harbour porpoise to narrowband frequency-modulated signals were measured using a behavioural method and an RT sensor based on infrared light. Equal latency contours, which connect equal RTs across frequencies, for reference values of 150-200 ms (10 ms intervals) were derived from median RTs to 1 s signals with sound pressure levels (SPLs) of 59-168 dB re. 1 μPa and centre frequencies of 0.5, 1, 2, 4, 16, 31.5, 63, 80 and 125 kHz. The higher the signal level was above the hearing threshold of the harbour porpoise, the quicker the animal responded to the stimulus (median RT 98-522 ms). Equal latency contours roughly paralleled the hearing threshold at relatively low sensation levels (higher RTs). The difference in shape between the hearing threshold and the equal latency contours was more pronounced at higher levels (lower RTs); a flattening of the contours occurred for frequencies below 63 kHz. Relationships of the equal latency contour levels with the hearing threshold were used to create smoothed functions assumed to be representative of equal loudness contours. Auditory weighting functions were derived from these smoothed functions that may be used to predict perceived levels and correlated noise effects in the harbour porpoise, at least until actual equal loudness contours become available. © 2014. Published by The Company of Biologists Ltd.


Neo Y.Y.,Leiden University | Seitz J.,Leiden University | Kastelein R.A.,Sea Mammal Research Company SEAMARCO | Winter H.V.,Wageningen University | And 2 more authors.
Biological Conservation | Year: 2014

Human activities in and around waters generate a substantial amount of underwater noise, which may negatively affect aquatic life including fish. In order to better predict and assess the consequences of the variety of anthropogenic sounds, it is essential to examine what sound features contribute to an impact. In this study, we tested if sounds with different temporal structure resulted in different behavioural changes in European seabass. Groups of four fish were exposed in an outdoor basin to a series of four sound treatments, which were either continuous or intermittent, with either consistent or fluctuating amplitude. The behavioural changes of the fish were analyzed by a video-tracking system. All sound treatments elicited similar behavioural changes, including startle responses, increased swimming speed, increased group cohesion and bottom diving. However, with all other sound conditions being the same, intermittent exposure resulted in significantly slower behavioural recovery to pre-exposure levels compared to continuous exposure. Our findings imply that the temporal structure of sound is highly relevant in noise impact assessments: intermittent sounds, such as from pile driving, may have a stronger behavioural impact on fish than continuous sounds, such as from drilling, even though the latter may have higher total accumulated energy. This study urges regulatory authorities and developers to pay more attention to the influence of temporal structure when assessing noise impacts. However, more studies are needed to examine other sound parameters and to determine the generality of our observations in other species and in other outdoor water bodies. © 2014 Elsevier Ltd.


Kastelein R.A.,Sea Mammal Research Company SEAMARCO | van Heerden D.,Sea Mammal Research Company SEAMARCO | Gransier R.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO
Marine Environmental Research | Year: 2013

The high under-water sound pressure levels (SPLs) produced during pile driving to build offshore wind turbines may affect harbor porpoises. To estimate the discomfort threshold of pile driving sounds, a porpoise in a quiet pool was exposed to playbacks (46strikes/min) at five SPLs (6dB steps: 130-154dB re 1μPa). The spectrum of the impulsive sound resembled the spectrum of pile driving sound at tens of kilometers from the pile driving location in shallow water such as that found in the North Sea. The animal's behavior during test and baseline periods was compared. At and above a received broadband SPL of 136dB re 1μPa [zero-peak sound pressure level: 151dB re 1μPa; t90: 126ms; sound exposure level of a single strike (SELss): 127dB re 1μPa2s] the porpoise's respiration rate increased in response to the pile driving sounds. At higher levels, he also jumped out of the water more often. Wild porpoises are expected to move tens of kilometers away from offshore pile driving locations; response distances will vary with context, the sounds' source level, parameters influencing sound propagation, and background noise levels. © 2013 Elsevier Ltd.


Kastelein R.A.,Sea Mammal Research Company SEAMARCO | Gransier R.,Sea Mammal Research Company SEAMARCO | Hoek L.,Sea Mammal Research Company SEAMARCO | Olthuis J.,Sea Mammal Research Company SEAMARCO
Journal of the Acoustical Society of America | Year: 2012

Safety criteria for underwater sound produced during offshore pile driving are needed to protect marine mammals. A harbor porpoise was exposed to fatiguing noise at 18 sound pressure level (SPL) and duration combinations. Its temporary hearing threshold shift (TTS) and hearing recovery were quantified with a psychoacoustic technique. Octave-band white noise centered at 4 kHz was the fatiguing stimulus at three mean received SPLs (124, 136, and 148 dB re 1 μPa) and at six durations (7.5, 15, 30, 60, 120, and 240 min). Approximate received sound exposure levels (SELs) varied between 151 and 190 dB re 1 μPa2 s. Hearing thresholds were determined for a narrow-band frequency-swept sine wave (3.9-4.1 kHz; 1 s) before exposure to the fatiguing noise, and at 1-4, 4-8, 8-12, 48, and 96 min after exposure. The lowest SEL (151 dB re 1 μPa2 s) which caused a significant TTS1-4 was due to exposure to an SPL of 124 dB re 1 μPa for 7.5 min. The maximum TTS1-4, induced after a 240 min exposure to 148 dB re 1 μPa, was around 15 dB at a SEL of 190 dB re 1 μPa2 s. Recovery time following TTS varied between 4 min and under 96 min, depending on the exposure level, duration, and the TTS induced. © 2012 Acoustical Society of America.

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