No, I never said that dither becomes a coherent signal. Dither is noise.
> On Jan 10, 2022, at 12:14 PM, Zhiguang Zhang <[email protected]> wrote: > > Vicki, > > that is rather incredible to me if true, that dither is detectable as a > coherent signal but i suppose that the dither that i was referring to is > necessarily a part of the program material signal because it is the dither > that has already been added during the recording chain and thus not a > separate coherent signal > > https://ask.audio/articles/the-how-and-why-of-dithering-in-pro-tools > <https://ask.audio/articles/the-how-and-why-of-dithering-in-pro-tools> > On Mon, Jan 10, 2022 at 9:15 AM vicki melchior <[email protected] > <mailto:[email protected]>> wrote: > Eric, I’m not sure I get the gist of your question, but “hearing into the > noise” refers to the fact that coherent signals can be detected at some level > (around 10-15 dB) below the RMS level of the noise (whether the noise is > dither or part of the signal). The mathematical analogy for this is > coherent/noncoherent gain; the hearing system integrates both noise and > signal over the bandwidth of the particular cochlear filter. Noise > integrates non-coherently while signal integrates coherently, leaving a net > gain in SNR. This is relevant for a number of reasons. First, you can > (maybe) detect actual signal at those depths below noise. But second, you > can also hear distortion lying well below the noise floor if it is relatively > coherent, especially the peaks associated with truncation distortion when > dither has been omitted. These arguments are highly relevant to determining > the bit depth needed to convey program material, and that in turn, is a > function of the dynamic range audible to humans along with an understanding > of the noise sources present in the given system. So it is not about hearing > the noise, but rather hearing signal below the noise floor. > > >> On Jan 9, 2022, at 8:10 PM, Zhiguang Zhang <[email protected] >> <mailto:[email protected]>> wrote: >> >> not sure if this point is important, but the dither that is added before you >> hear the program material being reproduced isn't actually supposed to be >> 'heard' - so this argument doesn't appear to make much sense in my mind. >> engineers might hear the dither when they're familiar with the studio that >> they work in, but past that, i'm not sure i get the point of discussing the >> practical limits of hearing something added which, for all intents and >> purposes, is hidden. it's almost like you're trying to reverse engineer >> what recording interface an audio engineer was using >> >> On Sun, Jan 9, 2022 at 5:48 PM Brian Willoughby <[email protected] >> <mailto:[email protected]>> wrote: >> Thank you for these titles. I've already found them in the AES library. >> >> Brian Willoughby >> >> >> On Jan 9, 2022, at 13:43, vicki melchior <[email protected] >> <mailto:[email protected]>> wrote: >> > As far as measurements of how far “into the noise” we can hear, there >> > aren’t a lot of good published numbers that I know of (having reviewed the >> > subject a couple of years ago), but Bob Stuart and Peter Craven argue >> > dynamic range and, to a certain extent, audibility below the noise floor >> > in a couple of papers published in JAES in 2019. They are based on >> > psychoacoustic arguments as well as listening test results, the latter as >> > part of their studio and lab work on MQA. If interested, their (open >> > access) papers are in the AES e-lib, “The Gentle Art of Dithering” and “A >> > Hierarchical Approach for Audio Capture, Archive and Distribution”. >
