Delphinid sonar: measurement and analysis

Diercks, K. J.; Trochta, R. T.; Evans, William E.

doi:10.1121/1.1913564

Cited by 23 publications

(11 citation statements)

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“…Heavy distortion of the signal and very powerful LF components appeared at all the tested input levels. We regard that as an artifact of too low tape speed as reported by Diercks et al ͑1973͒, and we infer that parts of the LF components reported in Amundin ͑1991a, 1991b͒ could have been created by this phenomenon.…”

Section: E Recording Of Artificial Porpoise Clicksmentioning

confidence: 99%

“…Due to the large difference in sound pressure of the HF and LF component ͑Amundin, 1991a͒, an analog tape recorder should not be able to record both components on the acoustic axis of the HF component on the same channel without distortion. It can therefore be hypothesized that the often prominent LF component reported from older studies using analog tape recorders could at least in part be an artifact generated by analog recording systems, as outlined by Diercks et al ͑1973͒. To test this hypothesis, we made recordings of clicks from free-swimming porpoises using a Reson TC4014 hydrophone connected to both a digital and an analog recorder via a 40 dB gain box with a first order high-pass filter at 100 Hz and an eight order 150 kHz antialiasing filter.…”

Section: Comparing Analog To Digital Recordingsmentioning

confidence: 99%

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Low-frequency components in harbor porpoise (Phocoena phocoena) clicks: communication signal, by-products, or artifacts?

Hansén

Wahlberg²,

Madsen

2008

The Journal of the Acoustical Society of America

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Underwater sound signals for biosonar and communication normally have different source properties to serve the purposes of generating efficient acoustic backscatter from small objects or conveying information to conspecifics. Harbor porpoises ͑Phocoena phocoena͒ are nonwhistling toothed whales that produce directional, narrowband, high-frequency ͑HF͒ echolocation clicks. This study tests the hypothesis that their 130 kHz HF clicks also contain a low-frequency ͑LF͒ component more suited for communication. Clicks from three captive porpoises were analyzed to quantify the LF and HF source properties. The LF component is 59 ͑S.E.M= 1.45 dB͒ dB lower than the HF component recorded on axis, and even at extreme off-axis angles of up to 135°, the HF component is 9 dB higher than the LF component. Consequently, the active space of the HF component will always be larger than that of the LF component. It is concluded that the LF component is a by-product of the sound generator rather than a dedicated pulse produced to serve communication purposes. It is demonstrated that distortion and clipping in analog tape recorders can explain some of the prominent LF components reported in earlier studies, emphasizing the risk of erroneous classification of sound types based on recording artifacts.

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Section: E Recording Of Artificial Porpoise Clicksmentioning

confidence: 99%

Section: Comparing Analog To Digital Recordingsmentioning

confidence: 99%

Low-frequency components in harbor porpoise (Phocoena phocoena) clicks: communication signal, by-products, or artifacts?

Hansén

Wahlberg²,

Madsen

2008

The Journal of the Acoustical Society of America

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“…Up to six specially constructed "suction cup" hydrophones were used to measure echolocation signals, a technique first used by Diercks et al ͑1973͒. Four of these hydrophones were the same as the ones used by Au et al ͑2006͒.…”

Section: B Hydrophone Geometrymentioning

confidence: 99%

The acoustic field on the forehead of echolocating Atlantic bottlenose dolphins (Tursiops truncatus)

Houser

Finneran

et al. 2010

The Journal of the Acoustical Society of America

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Arrays of up to six broadband suction cup hydrophones were placed on the forehead of two bottlenose dolphins to determine the location where the beam axis emerges and to examine how signals in the acoustic near-field relate to signals in the far-field. Four different array geometries were used; a linear one with hydrophones arranged along the midline of the forehead, and two around the front of the melon at 1.4 and 4.2 cm above the rostrum insertion, and one across the melon in certain locations not measured by other configurations. The beam axis was found to be close to the midline of the melon, approximately 5.4 cm above the rostrum insert for both animals. The signal path coincided with the low-density, low-velocity core of the melon; however, the data suggest that the signals are focused mainly by the air sacs. Slight asymmetry in the signals were found with higher amplitudes on the right side of the forehead. Although the signal waveform measured on the melon appeared distorted, when they are mathematically summed in the far-field, taking into account the relative time of arrival of the signals, the resultant waveform matched that measured by the hydrophone located at 1 m.

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“…Four specially constructed 'suction cup' hydrophones were used to measure echolocation signals, a technique first used by Diercks et al (Diercks et al, 1973). Each hydrophone consisted of a cylindrical piezoelectric element similar to the elements used in the Brüel and Kjaer 8103 hydrophones, but enclosed within a suction cup constructed of degassed polyurethane compound (Uralite 3138).…”

Section: Experimental Configuration and Approachmentioning

confidence: 99%

Acoustic radiation from the head of echolocating harbor porpoises(Phocoena phocoena)

Kastelein

Benoit‐Bird

et al. 2006

Journal of Experimental Biology

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SUMMARY An experiment was conducted to investigate the sound pressure patterns on the melon of odontocetes by using four broadband hydrophones embedded in suction cups to measure echolocation signals on the surface of the forehead of two harbor porpoises (Phocoena phocoena). It has long been hypothesized that the special lipids found in the melon of odontocetes, and not in any other mammals, focus sounds produced in the nasal region that then propagate through the melon, producing a beam that is directional in both the horizontal and vertical planes. The results of our measurements supported the melon-focusing hypothesis, with the maximum click amplitude, representing the axis of the echolocation beam, located approximately 5.6-6.1 cm from the edge of the animal's upper lip along the midline of the melon. The focusing is not sharp but is sufficient to produce a transmission beam of about 16°. Click amplitude dropped off rapidly at locations away from the location of site of maximum amplitude. Based on comparisons of forehead anatomy from similar sized porpoises, the beam axis coincided with a pathway extending from the phonic lips through the axis of the low-density/low sound velocity lipid core of the melon. The significant interaction between click number and hydrophone position suggests that the echolocation signals can take slightly different pathways through the melon, probably as a result of how the signals are launched by the production mechanism and the position of the acoustically reflective air sacs.

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Delphinid sonar: measurement and analysis

Cited by 23 publications

References 0 publications

Low-frequency components in harbor porpoise (Phocoena phocoena) clicks: communication signal, by-products, or artifacts?

Low-frequency components in harbor porpoise (Phocoena phocoena) clicks: communication signal, by-products, or artifacts?

The acoustic field on the forehead of echolocating Atlantic bottlenose dolphins (Tursiops truncatus)

Acoustic radiation from the head of echolocating harbor porpoises(Phocoena phocoena)

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