Related Experiment Video
Updated: Jan 18, 2026
07:13
A Two-interval Forced-choice Task for Multisensory Comparisons
Published on: November 9, 2018
11.4K
Chimaeric sounds reveal dichotomies in auditory perception
Zachary M Smith1, Bertrand Delgutte, Andrew J Oxenham
1Eaton-Peabody Laboratory, Massachusetts Eye & Ear Infirmary, Boston, Massachusetts 02114, USA.
Nature
|March 8, 2002
Summary
The study reveals that sound envelopes are crucial for understanding speech, while fine time structures are key for pitch and localization. Conflicting cues show envelope determines speech content and fine structure determines perceived location.
Area of Science:
- Auditory neuroscience
- Psychoacoustics
- Signal processing
Background:
- Fourier's theorem decomposes signals into sinusoids; the inner ear performs a mechanical Fourier transform.
- Hilbert's alternative decomposition separates signals into envelope and fine time structure.
- Auditory brainstem neurons are sensitive to these signal features.
Purpose of the Study:
- To investigate the relative perceptual importance of sound envelope and fine time structure.
- To understand how these features contribute to speech perception, pitch, and localization.
Main Methods:
- Synthesis of 'auditory chimaeras'—stimuli with the envelope of one sound and the fine structure of another.
- Perceptual evaluation of synthesized auditory stimuli.
Main Results:
- Sound envelope is most important for speech reception.
- Fine time structure is most important for pitch perception and sound localization.
- In conflicting stimuli, envelope dictates word identification, while fine structure determines perceived location.
Conclusions:
- Auditory perception relies on distinct processing of envelope and fine time structure.
- Findings suggest an acoustic basis for the auditory cortex's 'what' (speech) and 'where' (location) pathways.
Related Concept Videos
01:13The Cochlea
50.6K
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.
50.6K
01:17Auditory Perception
1.0K
The auditory system is essential for sound perception, utilizing various critical structures. When sound waves enter the outer ear, they travel through the ear canal and cause the eardrum to vibrate. These vibrations are then transmitted to the middle ear, where three tiny bones – the malleus, incus, and stapes – amplify the sound. This amplification is crucial, as it ensures that the sound vibrations are strong enough to be conveyed to the inner ear. These vibrations then reach the...
1.0K
01:01Perception of Sound Waves
5.4K
The human ear is not equally sensitive to all frequencies in the audible range. It may perceive sound waves with the same pressure but different frequencies as having different loudness. Moreover, the perception of sound waves depends on the health of an individual's ears, which decays with age. The health of one's ears may also be affected by regular exposure to loud noises.
The pitch of a sound depends on the frequency and the pressure amplitude of the source. Two sounds of the same...
The pitch of a sound depends on the frequency and the pressure amplitude of the source. Two sounds of the same...
5.4K
01:21Perceiving Loudness, Pitch, and Location
943
The human brain perceives pitch through two primary mechanisms reflected in place theory and frequency theory. Each mechanism describes how sound waves are interpreted as specific pitches by the brain, offering insights into the intricate processes of auditory perception.
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by...
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by...
943
02:25Chirality
29.1K
Chirality is a term that describes the lack of mirror symmetry in an object. In other words, chiral objects cannot be superposed on their mirror images. For example, our feet are chiral, as the mirror image of the left foot, the right foot, cannot be superposed on the left foot.
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
29.1K
01:10Interference: Path Lengths
1.9K
Consider two sources of sound, that may or may not be in phase, emitting waves at a single frequency, and consider the frequencies to be the same.
Two special sources may be considered when they are in phase. This can be easily achieved by feeding the two sources from the same source. An example would be synchronizing the two speakers by feeding them with the same source, such as the sound waves produced by a tuning fork. This setup ensures that the two sources have the same frequency and are...
Two special sources may be considered when they are in phase. This can be easily achieved by feeding the two sources from the same source. An example would be synchronizing the two speakers by feeding them with the same source, such as the sound waves produced by a tuning fork. This setup ensures that the two sources have the same frequency and are...
1.9K