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Old 25th Apr 2021, 11:24 am   #10
Radio Wrangler
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Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Default Re: Relative periodicity of non-harmonic oscillators

If you're listening to an SSB signal and adjusting the tuning, the apparent pitch of the audio slides. All audio components are offset by the same amount, so harmonic components are not in the right places compared to the fundamentals. This sounds wrong. Most people can detect the wrongness, but not put their finger on the reason why.

Twiddle the tuning and then at some point all the harmonics land on integer multiples of their fundamental's frequencies and it sounds 'right'.

For a bit of fun you can use an SSB receiver to demod one carrier of an AM station playing music. Frequency offset music sounds seriously weird!

In music and acoustics, frequency scaling by a multiplication factor is natural, and fits with our logarithmic perception of frequency. An additive/subtractive shift is very unnatural and can sound disquieting.

David
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