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] > <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”.
