 |
| Research article summary (published 29 Sep 2002): |
The auditory C-process of spectral profile analysis.
Full Abstract
OBJECTIVES:
We here review the findings of several experiments, aimed at clarifying the functional role of the human auditory cortex in the processing of complex sound mixtures.METHODS:
Long-latency auditory evoked potentials were recorded to abrupt changes in the pitch or timbre of continuous complex tones (synthesized musical instrument sounds). Changes were made at intervals of 0.5-4.5 s while the subjects read a magazine.RESULTS:
The main response was a P1/N1/P2 complex which was maximal at the vertex and symmetrically distributed, consistent with origin in the supratemporal cortices of both hemispheres. To distinguish them from the conventional responses to brief pure tones, the potentials were named CP1 (c. 55 ms), CN1 (90 ms) and CP2 (165 ms). Responses to changes of pitch, where all the spectral components changed frequency, and to changes of timbre, where the frequencies remained the same but their energy levels changed, were very similar to one another. The response amplitudes were little affected by the magnitude of frequency changes in the range 6-100%, but were strongly influenced by the rate at which changes occurred (requiring at least 4 s for full recovery) and by the breadth of the changing frequency spectrum (the upper partials of the tone in sum contributing more than the fundamental). When the C-potentials were made refractory by a high rate of pitch changes (16/s) within a narrow frequency range, responses could still be elicited by infrequently interspersed changes of timbre. When the tones were split into their high and low partials, the responses to change in the two frequency bands combined roughly algebraically.CONCLUSIONS:
The responses appear to represent a cortical process concerned with analysing the distribution of sound energy across the frequency spectrum ('spectral profile analysis'). This may be an important stage in the analysis of complex sound mixtures and in the perception of sound quality.
Learn Faster Today Improve your study skills
Author information
Author/s: Jones, S J (SJ); Perez, N (N);
Affiliation: Department of Clinical Neurophysiology, The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK. sjjones@ion.ucl.ac.uk
Journal and publication information
Publication Type: Journal Article
Journal: Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology (Clin Neurophysiol), published in Netherlands. (Language: eng)
Reference: 2002-Oct; vol 113 (issue 10) : pp 1558-65
Dates: Created 2002/09/27; Completed 2002/12/04; Revised 2008/09/10;
PMID: 12350431, status: MEDLINE (last retrieval date: 11/6/2008)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
External Links for this article (including full text providers, if available):
Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.
This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.
MeSH headings (categories)
This article was linked to the MESH Headings shown below.
|
Related articles
This article has not been indexed for related articles as yet, however you can still use the live related article search links below.
See a large map of 100+ related articles.