Clemins, P.J., M.T. Johnson, K.M. Leong, and A. Savage (2005). Automatic classification and speaker identification of African elephant (Loxodonta africana) vocalizations. Journal of the Acoustical Society of America 117(2): 956-63.
NAL Call Number: QC221.A27
Abstract: A hidden Markov model (HMM) system is presented for automatically classifying African elephant vocalizations. The development of the system is motivated by successful models from human speech analysis and recognition. Classification
features
include frequency-shifted Mel-frequency cepstral coefficients (MFCCs) and log energy, spectrally motivated features which are commonly used in human speech processing. Experiments, including vocalization type classification and speaker
identification,
are performed on vocalizations collected from captive elephants in a naturalistic environment. The system classified vocalizations with accuracies of 94.3% and 82.5% for type classification and speaker identification classification experiments,
respectively.
Classification accuracy, statistical significance tests on the model parameters, and qualitative analysis support the effectiveness and robustness of this approach for vocalization analysis in nonhuman species.
Descriptors: phonetics, signal processing, computer assisted, sound spectrography classification, speech acoustics, vocalization, animal classification, acoustics, animal identification systems classification, fourier analysis, Markov chains,
reproducibility
of results, sound spectrography statistics and numerical data.
Garstang, M. (2004). Long-distance, low-frequency elephant communication. Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology 190(10): 791-805.
NAL Call Number: QP33.68
Descriptors: communication, physiology, auditory threshold, hearing physiology, sex behavior, social behavior, sound, sound localization, vocalization, weather.
Leong, K.M., K. Burks, C.E. Rizkalla, and A. Savage (2005). Effects of reproductive and social context on vocal communication in captive female African elephants (Loxodonta africana). Zoo Biology 24(4): 331-347. ISSN: 0733-3188.
NAL Call Number: QL77.5.Z6
Descriptors: zoo animals, vocalization, social dominance, estrous cycle, hormone secretion, females, males, social behavior.
Leong, K.M., A. Ortolani, L.H. Graham, and A. Savage (2003). The use of low-frequency vocalizations in African elephant (Loxodonta africana) reproductive strategies. Hormones and Behavior 43(4): 433-43.
NAL Call Number: QP801.H7H64
Abstract: Fertility-advertisement calls in females are predicted to occur in nonmonogamous species where males and females are widely separated in space. In African elephants, low-frequency vocalizations have thus been suggested as a reproductive
strategy used by fertile females to attract mates. This study examined the use of low-frequency vocalizations with respect to different phases of the estrous cycle in African elephants by simultaneously monitoring vocalizations, behavior, and hormonal
profiles.
Subjects were one male and six female African elephants housed at Disney's Animal Kingdom. No acoustically distinct vocalizations were restricted to the ovulatory follicular phase. However, overall rate of low-frequency vocalization as well as the
rate of one acoustically distinct vocalization changed over the estrous cycle, with highest rates of calling related to the first period of follicular growth, or anovulatory follicular phase. Elevated rates of vocalization thus were not restricted to
behavioral
estrus and occurred much earlier in the estrous cycle than in most species that produce fertility-advertisement calls. Both herd composition and elephant identity also affected rates of vocalization. Vocalizations therefore may not be reliable
signals
of actual fertility. However, the increase in vocalizations in advance of estrus may attract males to the herd prior to ovulation, facilitating both male-male competition and female choice. Once present in the herd, males may then switch strategies to
use more reliable chemical and visual cues to detect ovulating females.
Descriptors: physiology, sex behavior, animal physiology, vocalization, estrous cycle physiology, luteinizing hormone blood, ovulation physiology, reproduction physiology, social behavior.
Leong, K., K. Burks, C. Rizkalla, and A. Savage (2005). Effects of reproductive and social context on vocal communication in captive female African elephants (Loxodonta africana). Zoo Biology 24(4): 331-347. ISSN: 0733-3188.
NAL Call Number: QL77.5.Z6
Descriptors: African elephant, Loxodonta africana, reproduction, acoustic signals, female vocalizations, communication, social context effects, LWP frequency vocalizations, long distances, social behavior.
Leong, K., A. Ortolani, K. Burks, J. Mellen, and A. Savage (2003). Quantifying acoustic and temporal characteristics of vocalizations for a group of captive African elephants Loxodonta africana. Bioacoustics 13(3): 213-231. ISSN:
0952-4622.
Descriptors: African elephant, Loxodonta africana, coumminication, acoustic signals, vocalizations, acoustic and temporal characteristics, low frequency, rumbles, complex repertoire.
McComb, K., D. Reby, and L. Baker (2003). Long-distance communication of acoustic cues to social identity in African elephants. Animal Behaviour 65: 317-29.
NAL Call Number: Film S-1802
Descriptors: communication, acoustic cues, long distance, social identity, infrasonic calls, low frequencies.
Payne, K.B., M. Thompson, and L. Kramer (2003). Elephant calling patterns as indicators of group size and composition: The basis for an acoustic monitoring system. African Journal of Ecology 41(1): 99-107. ISSN: 0141-6707.
NAL Call Number: 409.6 EA7
Descriptors: African elephants, Loxodonta africana, behavior, acoustic activity analysis, acoustic monitoring, acoustic signals, calling patterns, variation, group size, composition, Namibia, vocal activity, remote monitoring, calls, low
frequency, high frequency.
Language of Text: English, with English and French summaries.
Soltis, J., K. Leong, and A. Savage (2005). African elephant vocal communication. I. antiphonal calling behaviour among affiliated females. Animal Behaviour 70(3): 579-87.
NAL Call Number: Film S-1802
Descriptors: vocal communication, calling behavior, females, antiphonal.
Soltis, J., K. Leong, and A. Savage (2005). African elephant vocal communication. II. rumble variation reflects the individual identity and emotional state of callers. Animal Behaviour 70(3): 589-99.
NAL Call Number: Film S-1802
Descriptors: vocal communication, rumble variation, individual identity.
Wood, J.D., B. Mccowan, W.R. Langbauer Jr., J.J. Viljoen, and L. Hart (2005). Classification of African elephant, Loxodonta africana, rumbles using acoustic parameters and cluster analysis. Bioacoustics 15(2): 143-161. ISSN:
0952-4622.
Descriptors: African elephant, rumbles, acoustic parameters, cluster analysis, calls, types, vocalizations, feeding, resting, categorized.