Re: Creating Band-passed noise stimuli (Biao Tian PhD )

Subject: Re: Creating Band-passed noise stimuli
From:    Biao Tian PhD  <biao(at)LN.NIMH.NIH.GOV>
Date:    Wed, 11 Jun 1997 10:16:56 -0400

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 >filter. 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. Best Biao Tian 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 USA Phone: (202) 687-6438 Fax: (202) 687-0617 E-mail: biao(at)

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