Related Experiment Video
Updated: Jul 14, 2026
09:35
Investigating Outer Hair Cell Motility with a Combination of External Alternating Electrical Field Stimulation and High-speed Image Analysis
Published on: July 18, 2011
Forward and reverse waves in nonclassical models of the cochlea
1Room D2-226, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. e.d.boer@hccnet.nl
The Journal of the Acoustical Society of America
|June 7, 2007
Summary
Nonclassical cochlear models exhibit asymmetrical wave propagation. Forward waves are amplified, while reverse waves are attenuated, with phase patterns differing based on feedback mechanisms.
Area of Science:
- Auditory Neuroscience
- Biophysics
- Acoustics
Background:
- Classical cochlear models assume local mechanical properties of the cochlear partition, primarily the basilar membrane.
- Wave propagation in these classical models is symmetrical, regardless of direction (apexward or baseward).
- Nonclassical models incorporate spatially dependent mechanical properties, allowing for asymmetrical wave propagation.
Purpose of the Study:
- To analyze feed-forward and feed-backward models of cochlear mechanics.
- To investigate the properties of forward and reverse wave propagation in these nonclassical models.
- To understand how feedback mechanisms influence wave amplification, attenuation, and phase patterns.
Main Methods:
- Analysis of theoretical models incorporating spatially dependent mechanical properties.
- Focus on the mathematical description of wave propagation in forward and reverse directions.
- Comparison of wave properties between feed-forward, feed-backward, and non-feedback models.
Main Results:
- In both feed-forward and feed-backward models, forward waves experience amplification, while reverse waves undergo attenuation.
- The slope of the phase pattern remains similar for both forward and reverse waves.
- Feed-forward models increase the phase slope, whereas feed-backward models decrease it relative to models without feedback.
Conclusions:
- Nonclassical cochlear models with feedback demonstrate directional asymmetry in wave propagation.
- Wave amplification for forward propagation is coupled with attenuation for reverse propagation.
- Feedback mechanisms significantly alter the phase characteristics of cochlear wave propagation, impacting auditory signal processing.
Related Concept Videos
01:13The Cochlea
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.
01:22Hair Cells
Hair cells are the sensory receptors of the auditory system—they transduce mechanical sound waves into electrical energy that the nervous system can understand. Hair cells are located in the organ of Corti within the cochlea of the inner ear, between the basilar and tectorial membranes. The actual sensory receptors are called inner hair cells. The outer hair cells serve other functions, such as sound amplification in the cochlea, and are not discussed in detail here.
01:15Auditory Pathway
Auditory pathways constitute the complex neural circuits responsible for transmitting and interpreting auditory information from the peripheral auditory system to the brain. Sound waves are initially captured by the outer ear, funneled through the ear canal, and reach the tympanic membrane (eardrum). These vibrations are transmitted via the middle ear's ossicles to the inner ear's cochlea.
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
01:01Sound Waves
Sound waves can be thought of as fluctuations in the pressure of a medium through which they propagate. Since the pressure also makes the medium's particles vibrate along its direction of motion, the waves can be modeled as the displacement of the medium's particles from their mean position.
Sound waves are longitudinal in most fluids because fluids cannot sustain any lateral pressure. In solids, however, shear forces help in propagating the disturbance in the lateral direction as well. Hence,...
Sound waves are longitudinal in most fluids because fluids cannot sustain any lateral pressure. In solids, however, shear forces help in propagating the disturbance in the lateral direction as well. Hence,...
00:53Sound Waves: Interference
Sound waves can be modeled either as longitudinal waves, wherein the molecules of the medium oscillate around an equilibrium position, or as pressure waves. When two identical waves from the same source superimpose on each other, the combination of two crests or two troughs results in amplitude reinforcement known as constructive interference. If two identical waves, that are initially in phase, become out of phase because of different path lengths, the combination of crests with troughs...
01:16Anatomy of the Ear
Auditory sensation, commonly called hearing, involves the transformation of sonic waves into neural impulses facilitated by the structures of the auditory organ. The prominent, flesh-like structure on the side of the head, called the auricle, directs sound waves towards the auditory canal. The auricle is often mislabeled as the pinna, a term more aligned with mobile structures like a feline's external ear. The auditory canal penetrates the cranium via the external auditory meatus of the...