Dither—my explanation of how it keeps details below quantization level, Was: "Dither" (TOS #6) Options

[KMD]

To help with the understanding of dither, I am posting an explanation, of how signal details smaller than the quantization level are retained, after quantization, when Dither Noise is added to the source material.
A small signal detail with height less than the quantization level, and centred half way between two quantization steps, is too small to cross a quantization step. It is lost when the waveform is quantized. With a Dither Noise waveform added, the height of the two waveforms summed is occasionally greater than the quantization level. At these occasional points the waveform crosses a quantization step. So now when this waveform is quantized, although the result is noisy, the shape of the original signal detail is retained.
Discussion invited.

[KMD]

icstm - Thanks

pdq - true, that is another function of dither. Frequently flipping the LSB by the sum of the small signal and the dither noise retaines the correct shape.