Frozen noise generation ("Enrique A. Lopez-Poveda" )

Subject: Frozen noise generation
From:    "Enrique A. Lopez-Poveda"  <enrique.lopezpoveda(at)UCLM.ES>
Date:    Fri, 13 Dec 2002 10:59:38 +0100

Dear list, We would appreciate your expertise in the following problem. We wish to generate two ".wav" files, each containing a burst of frozen noise (N1 and N2) of the same duration (say 200 ms) but with different frequency content. Let's say that N1 has frequency components from 10 Hz to 3000 Hz, and N2 from 3001 Hz to 4000 Hz. Most importanly, we wish that the SPL level for all frequencies be equal within each noise and equal for the two noises. So far, we have attempted to generate the noise by adding a large number of equal-amplitude, random phase tones (phases are uniformly distributed between 0 and 2pi). We then normalize each of the noises to their maximum amplitudes to produce a wav file. The result is that the spectrum of each noise is flat over their respective frequencies. However, the levels are different for the two noises (remember we wish for them to be equal). It is lower for the noise with the largest number of frequency components. This is probably the result of the normalization prior to producing the wav file. Is there a clever (analytical) solution to our problem, or do we have to adjust the level of noises manually to make them equal? Thank you very much in anticipation. -- Enrique Please note my new e-mail address: Enrique.LopezPoveda(at) Dr. Enrique A. Lopez-Poveda Facultad de Medicina Tel. +34-967599325 Universidad de Castilla-La Mancha Fax. +34-967599327 / 967599272 / 967599204 Campus Universitario 02071 Albacete, Spain

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