ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753350

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Whales, dolphins and porpoises, 80 species of entirely aquatic mammals, constitute the order Cetacea. In the early Eocene, about 55 to 60 million years ago according to paleontologists, distant ancestors of modern cetaceans left land for aquatic life. Cetaceans are diverse; average adult size of cetacean species varies by 1000 to 2000 times. Small and large species occupy all oceans from the equator to the polar seas, some forms inhabit rivers and four species live only in fresh water.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753351

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Bottlenose dolphinsTursiops truncatusproduce individually distinctive signature whistles. Dolphins recognize the signature whistles of animals with which they share a social bond. Signature whistles develop within the first few months of life and are stable for a lifetime. Vocal learning appears to play a role in the development of signature whistles in bottlenose dolphins. The signature whistles of most female dolphins and about half of male dolphins differ from those of their mothers. Some dolphin calves born in captivity develop a signature whistle that matches either man-made whistles or those of an unrelated dolphin. Dolphins retain the ability as adults to imitate the whistles of animals with which they share strong individual-specific social relationships, bonds which may change throughout their lifetime. The exceptional imitative abilities of dolphin infants and the retention of this ability in adults may be related to the maintenance of changing individual specific social relationships. Individual recognition by the voice may differ in marine vs terrestrial mammals. Diving marine mammals may not be able to rely upon involuntary voice cues for individual recognition, but rather may require vocal learning to maintain a stable signature as their vocal tract changes shape with increasing pressure during a dive.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753352

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Mysticete (baleen) whales produce a variety of vocalizations and sounds, but relatively few of these have been well described with accompanying behavior. This review concentrates on the vocalizations consistently associated with behavioral interactions or acoustic exchanges between or among conspecifics. These communication “signals” have been categorized for this review as contact calls of single animals outside of the breeding season (including cow-calf pairs), vocalizations reported during the breeding season (often designated as “songs”), and calls produced by active groups of whales that may or may not have a reproductive function. While much remains unknown, the data obtained thus far indicate that the social vocalizations of baleen whales have structural/functional similarities with those of other mammals and birds.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753353

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The dolphin continues to capture the imagination of investigators because of its ability to echolocate. Echolocation is essentially a special extension and adaptation of the dolphin's hearing system, coupled with the animal's ability to generate special sounds. Humans have demonstrated the ability to judge room size based on reverberation from a voice, and some of the visually challenged use self-generated sounds to detect large reflective objects. Echolocation represents a highly refined acoustic ability on a broad acoustic sensory continuum. Research on the auditory and echolocation performance of cetaceans has moved forward slowly due to limited animal resources and the general high cost of maintaining these animals in a laboratory environment.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753354

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The preponderance of our knowledge concerning hearing in the Cetacea has come from psychophysical studies. The most widely used alternative to psychophysical studies are neurophysiological studies utilizing auditory evoked potentials (AEPs). Due in part to the hypertrophy of auditory structures exhibited by the Cetacea, AEPs are highly robust and rapidly and easily obtained. Moreover, because AEPs reflect the synchronized activity of large neuronal assemblies, they offer a high level window onto auditory processing and allow for across-species comparison of responses.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753355

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Ultrasonic echolocation abilities are well documented in several dolphin species, but hearing characteristics are unknown for most whales. Vocalization data suggest whale hearing spans infra- to ultrasonic ranges. This paper presents an overview of whale ear anatomy and analyzes 1) how whale ears are adapted for underwater hearing and 2) how inner ear differences relate to different hearing capacities among whales.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753356

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Dolphins possess a highly sophisticated auditory system and a keen capability for echolocation. Signals are emitted in the form of high intensity, short duration, broadband exponentially decaying pulses. The frequency spectra of echolocation signals used by many dolphins are dependent on the output intensity of the signals and not on any fine tuning by the animals. When the output intensity is low, the center frequency of the click tends to be low. As the output intensity increases, the center frequency also tends to increase. The pulses propagate from the dolphin's melon in a relatively narrow beam, and echoes are received via the lower jaw, with a slightly wider beam. Echo- locating dolphins can detect targets at ranges of approximately 100 plus meters, depending on the size of the targets. Target discrimination experiments have shown that dolphins can discriminate the shape, size, material composition and internal structure of targets from the echoes. The broadband short duration properties of the signal allow the echoes to have high temporal resolution, so that within the structure of the echoes a considerable amount of information on the properties of the target can be conveyed. A brief comparison between the bat and dolphin sonar system will also be made. Bats typically emit much longer signals and a wider variety of different types of signals than dolphins. Signals used by some bats are suited to detecting Doppler shift, whereas the dolphin signal is designed to be tolerant of Doppler effects.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753357

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

This paper provides our views on the areas of cetacean bioacoustics that are in the greatest need of study over the next several years. In doing this, we ask a number of questions we see as important to developing a better understanding of cetacean bioacoustics. The topics we will cover are: Auditory Capabilities, including hearing sensitivity, pathways of sound to the ear, intraspecific variation in hearing capabilities, and the effects of intense sound on hearing capabilities; Echolocation, including the information-bearing parameters exploited by dolphin sonar systems to discriminate and identify objects, and the functional characteristics of the internal representation generated by reflections from ensonified objects; and Acoustic Communication, including the nature of the cetacean sound generation mechanism, the behaviors associated with mysticete communication sounds, and the range over which mysticetes communicate. While other investigators may not fully agree with our suggestions as to which questions are most important for future studies of cetacean bioacoustics, it is clear that a considerable effort must still be made in order that we can better understand the bioacoustics and general behavior of these animals.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753358

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753359

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor