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Re: Creating Band-passed noise stimuli
On Thu, 5 Jun 1997 16:48:25 Fatima Husain wrote
>I am in the process of creating stimuli which are white noise bandpassed
>through a filter. Basically I need a series of complex stimuli
>centerd at different frequencies. I tried harmonic complexes but
>found they can show beat and/or timbre effects which i could not control
>for. I need the stimuli to change in a more or less orderly manner,
>i.e. an individual shouldn't stand out from its neighbors (except
>for the change of freq./pitch effects).
>I have now settled for white noise bandpassed through say a butterworth
We use the SIGNAL program written by Kim Beeman (Engineering Design,
Belmont, MA) to generate random noise, then band-pass filter it. The
program is based on a DOS platform. By varying the lower and upper cut-off
frequencies, you can change both the center frequency and bandwidth. The
result is a narrow band noise with a certain pitch quality. Using the
band-passed noises (BPN) at different center frequencies, we have explored
the lateral belt on the superior temporal gyrus of the rhesus monkey and
found three quasi-tonotopic areas there (Rauschecker et al., 1995). We are
continuing using BPN to explore the response properties in the nonprimary
areas of the auditory cortex.
Rauschecker JP, Tian B, Hauser M (1995) Processing of Complex Sounds in the
Macaque Nonprimary Auditory Cortex. Science 268:111-114.
Biao Tian Ph.D.
Georgetown University Medical Center
Institute for Cognitive and Computational Sciences
The Research Bldg, WP24B
3970 Reservoir Rd. NW
Washington, DC 20007-2197
Phone: (202) 687-6438
Fax: (202) 687-0617