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Re: Secondary Harmonics

Subject: Re: Secondary Harmonics
From: Walter Knapp <>
Date: Wed, 04 Jun 2003 13:25:41 -0400
> In a message dated 6/3/03 4:16:45 PM Pacific Daylight Time,  
> writes:
>>Yes, real-time spectrogram applications may add spurious harmonics 
>>because they need to use simpler algorithms in order to execute fast 
>>enough on slower machines. However, a good off-line spectrogram 
>>software should not introduce any false harmonics. 
> Dear Experts,
> Does anyone know if CoolEdit Pro's spectrogram would add spurious harmonics?

I don't run cooledit, but have seen harmonics in sonograms others have 
done  which don't show up in some of my sonogram programs.

Note I get far more false harmonics out of my off-line sonogram program 
than I do off the realtime sonograms from Spark XL. Regardless of which 
calculation options I use. Each type of calculation has different stuff 
it's likely to show that's not there. It's all part of becoming familiar 
with the particular sonogram programs you use.

The easy way to find out is simply to do your filtering and see if they 
are filtered out or not. Note that usually false harmonics are very 
sound intensity dependent, typically only turning up on high intensity 

As far as slower machines, modern machines are so much more capable than 
those for which all these programs were written there is little reason 
to dumb down the programs. They do often have to be rewritten from the 
ground up to properly do realtime sonograms.



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