Quantization Grid, Split from Topic ID #55966 Options

[KMD]

I have thought that this phenomana may be real for years . I call it the "quantiztion grid". An analog waveform can change direction or cross the zero line at an infinite number of locations. Sampling and Quantization create a grid to which features of the waveform are statistically constrained. Increasing the sample rate at a fixed bandwidth inreases the quantization grid density. Whether it is perceivable is what is in question. This experiment may have proved it. I will give some thought to a simillar experiment that forum members can do for themselves and start a new topic on it.

[KMD]

ivqci - I am talking about regularity in the shape of the waveform

[2Bdecided]

ivqci - I am talking about regularity in the shape of the waveform

Yes, and what you say is true - easily visible in the waveform, and sometimes visible on a scope (depends on the DAC).

However, there's no mechanism in the ear to pick out that regularity. Once you do any kind of filtering (and the ear contains a continuum of bandpass filters), it disappears. You're just left with what looks like random noise.


Also, the error signal (original minus quantised = dither + quantisation error) contains remnants of the original signal. The classic Lipschitz and Vanderkooy dither paper from 1984 (I think!) showed graphs of error signals for various orders of dither. rectangular = first order, triangular = second order. More orders add more noise, but make the error even less correlated with the original. As the ear seems insensitive to higher orders of correlation, there's no need to go further.

This is all ignoring the real noise and signal levels in most recordings which make this (and even dither itself) academic.

Cheers,
David.