Related Experiment Video
Updated: Jul 7, 2026
11:15
fMRI Mapping of Brain Activity Associated with the Vocal Production of Consonant and Dissonant Intervals
Published on: May 23, 2017
Frequency modulation during song in a suboscine does not require vocal muscles.
Ana Amador1, Franz Goller, Gabriel B Mindlin
1Departamento de Física, FCEyN, Universidad de Buenos Aires, Argentina. anita@df.uba.ar
Journal of Neurophysiology
|February 22, 2008
Summary
Sound production in suboscine birds like the Great Kiskadee is not controlled by syringeal muscles. Air sac pressure, not neural signals, dictates sound frequency, challenging previous assumptions about avian vocalization.
Area of Science:
- Avian physiology
- Bioacoustics
- Evolutionary biology
Background:
- Sound production in suboscine birds remains under-investigated.
- Suboscines are believed to develop song innately, contrasting with oscine birds.
- Comparative phonatory mechanisms offer insights into vocal learning evolution.
Purpose of the Study:
- Investigate sound production and frequency control in the Great Kiskadee (Pitangus sulfuratus).
- Determine the role of respiratory activity versus syringeal muscles in vocalizations.
- Explore the underlying mechanisms of frequency modulation in suboscine birds.
Main Methods:
- Recorded air sac pressure and vocalizations during spontaneous song in Great Kiskadees.
- Performed bilateral resection of the tracheosyringeal nerve to denervate syringeal muscles.
- Analyzed the correlation between fundamental frequency and air sac pressure before and after denervation.
Main Results:
- Modulations in fundamental frequency strongly correlated with air sac pressure in all recorded vocalizations.
- This correlation remained unchanged after denervation of syringeal muscles.
- A single linear regression accurately described the relationship between sound frequency and air sac pressure in both intact and denervated birds.
Conclusions:
- Syringeal muscles do not appear to control sound frequency in the Great Kiskadee, contrary to songbirds.
- Air sac pressure is the primary regulator of sound frequency in this suboscine species.
- A theoretical two-mass model suggests nonlinear restitution forces are crucial for reproducing observed frequency modulations.
Related Concept Videos
01:22Muscle Stimulation Frequency
The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
01:06Forced Oscillations
When an oscillator is forced with a periodic driving force, the motion may seem chaotic. The motions of such oscillators are known as transients. After the transients die out, the oscillator reaches a steady state, where the motion is periodic, and the displacement is determined.
01:07Damped Oscillations
In the real world, oscillations seldom follow true simple harmonic motion. A system that continues its motion indefinitely without losing its amplitude is termed undamped. However, friction of some sort usually dampens the motion, so it fades away or needs more force to continue. For example, a guitar string stops oscillating a few seconds after being plucked. Similarly, one must continually push a swing to keep a child swinging on a playground.
Although friction and other non-conservative...
Although friction and other non-conservative...
01:17Standing Waves
Sometimes waves do not seem to move; rather, they just vibrate in place. Unmoving waves can be seen on the surface of a glass of milk kept in a refrigerator, which is one example of standing waves. Vibrations from the refrigerator motor create waves on the milk that oscillate up and down but do not seem to move across the surface. These waves are formed or created by the superposition of two or more identical moving waves in opposite directions. The waves move through each other, with their...
01:30Oscillations In An LC Circuit
An idealized LC circuit of zero resistance can oscillate without any source of emf by shifting the energy stored in the circuit between the electric and magnetic fields. In such an LC circuit, if the capacitor contains a charge q before the switch is closed, then all the energy of the circuit is initially stored in the electric field of the capacitor. This energy is given by
01:22Motional Emf
Magnetic flux depends on three factors: the strength of the magnetic field, the area through which the field lines pass, and the field's orientation with respect to the surface area. If any of these quantities vary, a corresponding variation in magnetic flux occurs. If the area through which the magnetic field lines are passing changes, then the magnetic flux also changes. This change in the area can be of two types: the flux through the rectangular loop increases as it moves into the magnetic...