Sound production of the humpback whale (Megaptera novaeangliae, Borowski) in Newfoundland waters
Sounds produced by humpback whales, Megaptera novaeanglise, were recorded in Newfoundland inshore waters. Only the acoustic features of the sounds were available for classification. Because of the variability present in the data, measurements such as minimum and maximum frequency, duration, etc, wer...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
1984
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| Online Access: | https://research.library.mun.ca/7862/ https://research.library.mun.ca/7862/1/Chabot_Denis.pdf https://research.library.mun.ca/7862/3/Chabot_Denis.pdf |
| Summary: | Sounds produced by humpback whales, Megaptera novaeanglise, were recorded in Newfoundland inshore waters. Only the acoustic features of the sounds were available for classification. Because of the variability present in the data, measurements such as minimum and maximum frequency, duration, etc, were inadequate for establishing a catalog. A new coding method was experimented with, where each sound was digitized into a matrix (16 x 21) of binary data. This was done using a digitizing tablet and a spectrogram of the sound. Additional binary variables were subsequently added to the matrices to code for relative intensity within a sound and frequency and amplitude modulation. A total of 1255 sounds were digitized and clustered using average linkage cluster analysis and the Jaccard similarity coefficient for binary data. -- The classification obtained by cluster analysis was compared with the author's aural and visual impressions of the sounds. A final classification of 50 classes was obtained. These classes were arranged in 13 groups. Three modes of sound production were recognized: respiratory noises, percussion noises, and vocalizations. Most classes (46) recognized in this study appeared to be vocalization. Some sounds were found to be tonal, but many had noisy and pulsive components. Few classes were stereotyped: variability was often important within classes, and intermediate cases were often found between classes, suggesting that part of the humpback's repertoire is a continuum of graded signals. -- Frequency of occurrence of each class varied from 1 to 94. A few classes were very common: the five largest classes accounted for 53.1% of the data. Twelve classes had only one case. This catalog is essentially complete for the location and seasons sampled, as suggested by an estimate of sample coverage and the rate of discovery of new classes with increasing sample size. -- Direction finding devices and playback experiments should be used to assess if humpback whales can discriminate these sound classes, and ... |
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