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We teach theoretical and practical basics of our research area in frames of the course «Bioacoustics of vertebrates» at the Faculty of Biology of the Lomonosov Moscow State University. This course is commonly in spring semester and addressed to 3rd-year students specializing on the cathedra of vertebrate zoology. In the course, the theoretical lectures alternate with the practical tasks. During the practical tasks, the students acquire modern methods and possibilities for measuring and analysis of acoustical parameters in calls of mammals and birds recognize the principles of their registering in the field and in the laboratory conditions. The practical tasks are made by student using contemporary bioacoustical equipment and professional software for sound analysis (including also software available for free from Internet). This set of practical tasks is an essential set for resolving the questions arising during the real scientific research. These practical tasks allow students to know the basics of the bioacoustical research on particular examples, doing the practical work themselves. We will be glad if this practicum will be useful to all who is interest in animal vocalizations.
The practical part of the course «Bioacoustics of vertebrates» uses the textbook «Practical guide for bioacoustics», describing in details all the tasks, made by students during the practicum.
Aims and tasks of the course: to provide students current knowledge about the structure of animal vocalizations and ways of their analysis, basic anatomy and functions of vocal apparatus in mammals and birds, approaches for classifying the vocal repertoires, communicative aspects of acoustic behaviour, similarities and differences of animal sounds and human speech. Along to the lectures, we conduct Practicum for bioacoustics, on the practical skills of recording of animal calls and analysis of their acoustic structure using professional software for sound analysis.
From the course, you will know:
- what is the call and what and how can be measured in it
- how the larynx of mammals and bird syrinx are arranged and work
- how many ways are there to produce sound
- what is the difference between animal sound and human speech
- how can one judge the evolution of speech without reliable paleontological data
- why animals “honestly” advertise by sounds about own size, emotions and physiological state
- what information about the animal is contained in the sound and how to extract it
- how people and animals learn about each other’s emotional state by sounds
- you will also learn about the capabilities and use the modern sound processing programs.
Structure of the course:
- Sound physics, parameters of sound wave. What and how can be measured in the sound. Sound wave as oscillatory process, time, frequency and power spectra of animal calls, call oscillogram (waveform) and spectrogram, measuring call duration, frequency and amplitude.
- Vocal production in mammals: Anatomy and the acoustics. Sound sources and modifying sound signal by the vocal tract. General scheme of arrangement of the vocal apparatus in vertebrates, the lungs as the generator of airflow. Transformation of airflow energy into the acoustic energy in the voice source. General scheme of arrangement of the larynx in mammals and syrinx in birds. Myoelastic theory of vocal fold oscillations. Call fundamental frequency and harmonics. The role of the vocal tract in the filtering of the sound source signal. The nose and sound nasalization. Formants: vocal tract resonances. Calculating the formant frequencies via the vocal tract length. Theory of independence of the vocal source and vocal tract.
- Morphological diversity of vocal systems in vertebrates. Influences of different morphological structures on call characteristics. Two-voice phenomena in birds. Hypertrophied vocal sources in mammals. Morphology of the vocal folds, vocal membranes and vocal pads on the vocal folds. Modifying the focal tract (evolvement of the tracheal elongations, enlargement of the nasal cavity, descent of the larynx). Air sacks.
- Information about body size in the calls, the anatomical and physiological restrictions. Relationship between body size and possibility of sound propagation in the environment. Lung volume, source, the length of the vocal tract as vocal source to body size. Syrinx monofunctionality and larynx polyfunctionality.
- Ways of sound production in mammals and birds. Phonations, purring, turbulence (noise and true whistle). Possibility of joint work of the two mechanisms.
- Nonlinear phenomena in vocalizations of mammals and birds. Their structural traits, occurrence and functional meaning. Limit cycle of the vocal fold oscillations. Subharmonics, deterministic chaos. Biphonation, sidebands and beating. Physiological basis of nonlinear phenomena. Frequency of nonlinear phenomena and their communicative meaning. Evolution of vocal behaviour.
- Approaches to call classification and describing vocal repertoires. Call types, are they real? Structural and functional approaches. Classification from viewpoints of discreetness and continuality. Discreetness of call types at the level of brain substrate and continuality as the result of the work of the vocal apparatus.
- Animal calls and human speech. Evolution of speech, anatomical and bioacoustical approaches to speech studying. Descent of human larynx and loss of air sacks. Development of fine motor control and vocal imitations. Limitations of paleontological data. Comparative approach: formants in animal communication, functions of vocal imitation.
- Neural control of vocalizations in mammals and humans. Similarity and differences. Sounds not related to emotions: primary and secondary neural substrates. Transit of sounds not related to emotions, under operant control. Similarity and differences in cerebral control of mammalian calls and human speech. Functions of acoustic behaviour.
- Approaches to studying communication: ethological, informational, regulatory (assessment-management). Applying to acoustic communication. Hypothesis of sensory exploitation. Evolutionary restrictions to vocal dishonesty.
- Far-distant communication. Limitations imposed by environment on sound structure. Sound degradation. Effect of habitat and time of day. «Acoustic windows». Influence of humidity, wind and relief complexity. Vibrational sounds. Burrow as an acoustic device.
- Ranging hypothesis: actual and apparent estimation of distance to caller. Vocal repertoires and dialects. Degradation of sound at propagation through the environment. Echo, decrease of intensity, frequency-dependent fading. Estimation by receiver the distance to call sender and possibility of deception via the effect of "close-range sounding". Development of different call types by songbirds and evolvement of vocal dialects.
- Close-distant communication. Morton’s motivation-structural rules. Hypothesis of expressive symbolism of body size. Relationship of sound acoustic structure and internal (motivational) state of a caller. Sounds o certain structure as unconditional stimulus common for all terrestrial vertebrates.
- Close-range communication. Hypothesis of emotional learning. Influencing the calls on a receiver: immediate (directly via action to nervous system) and emotionally conditioned (via stimuli related to the sounds). Cross-cultural parallelisms in sounds used by human dog trainers.
- Referential hypothesis: «messages» about particular objects or events. Arguments pro and contra the referential relationship between calls and certain events. Arbitrariness of call structure in relation to function. Interspecies communication. Apparent similarity and differences in mechanisms of evolving animal acoustic communication and human speech. Mutual teaching as the basis of intra and interspecies communication. Applied bioacoustics.
- Applied aspects of bioacoustics. Potentials of acoustical approach: contactless, fast, non-expensiveness. In captivity: determining species and subspecies, sexing, control of physiological state, acoustic stimulation of breeding. In the wild: long-term acoustic monitoring, determining species and sexual composition, luring (acoustic traps), population number counts, long-term monitoring of particular individuals and groups. Ecoacoustics: estimating the quality of natural landscapes on the basis of automated acoustic monitoring.
PRACTICAL WORKS
Task 1. Manual measurements of main time-frequency parameters using the software Avisoft-SASLab Pro. Statistical analysis of quantitative variation of calls.
Task 2. Visual analysis of acoustic variation of the calls, determining «signature» calls. Comparison of results of quantitative and qualitative (visual) analyses
Task 3. Diversity of nonlinear phenomena in calls of mammals and birds. Measuring fundamental frequency in calls containing nonlinear phenomena.
Sound files for the work at the practical lesson:
Task 4. Vocal repertoires and methods for catalogizing the calls. Additional possibilities of Avisoft-SASLab Pro software (automatic measurement of call parameters, labeling fragments of recording, filtering etc.) and main options of Syrinx and Audacity software (visual inspection and labeling of the calls).
Sound files for the work at the practical lesson:
Other materials:
Task 5. Tracking and measuring the fundamental and formant frequencies of calls using Praat software.
Sound files for tracking and measuring the fundamental frequency:
Other materials:
Example Excel Table for saving the exportable data from Praat software
Task 6. Recording animal calls for conducting the bioacoustical studies: choice of equipment and basic rules for the work in the field conditions.
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