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Critical Bands
By Theresa Veltri
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Band
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A range of frequencies.
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The middle of the band is called the centre frequency.
+ Critical Band
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A range of frequencies which are perceived by the ear as the
same pitch.
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All frequencies in a critical band activate the same area on
the basilar membrane.
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Place Theory
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Auditory Filter
Tonotopic map of the
human cochlea
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Critical Bandwidth

The distance needed between two frequencies in order for a
difference in pitch to be perceived.

Two frequencies must be at least one critical bandwidth apart.
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This measure 1.2mm on the basilar membrane.
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Incorporates approximately 1300 hair cells.
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Approximately 100Hz for low frequencies (200-600Hz).
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As frequencies increase, so does their critical bandwidth.
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
880Hz; 146. 67Hz
1/6 is between a M2-m3
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Frequency Difference
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Critical Bandwidth can be measured or quantified through
frequency difference.
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If the frequency difference is 0 = unison
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Rising and falling intensity
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If the two frequencies have band widths which largely overlap you
will hear beats.
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As the bandwidths overlap beats quicken producing dissonance
and a sensation of roughness.
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Pitches < m3 sound dissonant
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Critical Bandwidth Examples

Atonal music; tone clusters
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Auditory example
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Two sine waves at 400Hz. One gradually increases to 510Hz.
Tuning a Stringed instrument
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References

Cook, P. R. (1999). Music, cognition, and computerized sound:
An introduction to psychoacoustics. London, England:
The MIT Press.

Deutsch, D. (1999). The psychology of music, 2nd ed. London,
England: Academic Press.

Radocy, R. E. & Boyle, D. J. (2003). Psychological foundations of
musical behavior, 4th ed. Springfield, USA: Charles C. Thomas
Publisher, ltd.

Trainor, L. (2008). The neural roots of music. Nature, 53, 598-599.

Truax, B. (1999). Handbook for acoustic ecology, 2nd ed.
Burnaby, Canada: ARC Publications. Retrieved 2 October,
2009, from Simon Fraser University, World Soundscape
Project: http://www.sfu.ca/sonic-studio/handbook/Sound/
Critical_Band.aiff