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Re: Ping JJ

Masking works inside of a critical bandwidth, which is about 80-100 Hz at low frequencies and about 1/3 to 1/4 octave at high frequencies. (that means it turns over from uniform to geometric at 700 to 800 Hz or so)

If something is in a different critical band, it's less masked.

Now, the IM is a BIG problem because masking spreads UPWARDS in frequency, and just barely (i.e. almost not at all) more than 1/2 critical bandwidth down in frequency.

So if you intermod 19 and 20kHz and the distortion product is way down, you may well hear the 1kHz intermod clearly, even if the two initial tones are nearly inaudible due to being too high to hear.

This is one of the problems, in fact, with some of the extended bandwidth tests, the equipment had intermod that created signals much lower than the HF signals they intended to test.

The tutorial on perceptual coding I cited below has some plots that can give you a few examples.

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  • Re: Ping JJ - real_jj 19:07:17 06/14/06 (1)
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