Acoustic communication is a vital aspect of animal behavior, enabling species to convey information through sound. From to , animals have evolved diverse mechanisms to produce and perceive acoustic signals for various purposes.
Sound properties like , , and duration shape how animals communicate. These signals serve crucial functions in , territorial defense, and group coordination, influenced by environmental factors and evolutionary pressures.
Types of acoustic communication
Vocal communication
Non-vocal acoustic signals
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Top images from around the web for Non-vocal acoustic signals
Hissing of geese: caller identity encoded in a non-vocal acoustic signal [PeerJ] View original
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Hissing of geese: caller identity encoded in a non-vocal acoustic signal [PeerJ] View original
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Mechanisms of sound production
Vocal cords and syrinx
Vocal cords are two folds of tissue in the larynx that vibrate to produce sound in mammals
Air passing through the vocal cords causes them to vibrate, generating sound waves
The is the vocal organ in birds, located at the junction of the trachea and bronchi
Syrinx consists of membranes and muscles that vibrate to produce a wide range of sounds
Birds can control the frequency and amplitude of their vocalizations by adjusting the tension and position of the syringeal membranes
Some birds have a two-part syrinx, allowing them to produce two different sounds simultaneously
Stridulation and percussion
Stridulation is a method of sound production by rubbing body parts together, commonly used by and some vertebrates
Crickets and grasshoppers stridulate by rubbing their wings together, with one wing bearing a file-like structure and the other a scraper
The file and scraper mechanism creates vibrations that are amplified by the wings, producing the characteristic chirping sound
involves striking or tapping body parts against a substrate or other body parts to create sound
Woodpeckers drum on trees with their beaks to establish territories and attract mates
Some insects, like the death-watch beetle, create tapping sounds by striking their heads against wood
Properties of acoustic signals
Frequency and pitch
Frequency refers to the number of sound wave cycles per second, measured in Hertz (Hz)
is the subjective perception of frequency, with higher frequencies perceived as higher pitches
Different animal species produce and perceive sounds across a wide range of frequencies
and communicate using low-frequency infrasound (below 20 Hz), which can travel long distances
Many insects and some use high-frequency ultrasound (above 20 kHz) for communication and echolocation
The fundamental frequency of a sound determines its pitch, while harmonics contribute to the timbre or quality of the sound
Amplitude and loudness
Amplitude is the maximum displacement of a sound wave from its resting position, determining the energy or intensity of the sound
is the subjective perception of sound intensity, influenced by both amplitude and frequency
Sound intensity decreases with distance from the source, following the inverse square law
Animals can adjust the amplitude of their vocalizations to communicate over different distances and in various contexts
Loud , such as those of howler monkeys and lions, serve to advertise territories and intimidate rivals
Soft, low-amplitude vocalizations, like the purring of cats or the whispers of humans, are used in close-range, intimate communication