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 On Mon, Jan 10, 2022 at 9:15 AM vicki melchior <[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]> 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]> > 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]> 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”. >> > >
