In passing your math looks correct but I don't think that's the right way to assess the resolution of the system here. The sample rate has a fixed spacing. Eac

In passing your math looks correct but I don't think that's the right way to assess the resolution of the system here. The sample rate has a fixed spacing. Each sample will have some amplitude. Your ear reconstructs the sinusoid from these discreet samples. In general, as long as we're well below the Nyquist frequency (https://en.wikipedia.org/wiki/Nyquist_frequency https://en.wikipedia.org/wiki/Nyquist_frequency) the question (AFAIK) is how much jitter exists in the horizontal (time) and vertical (amplitude) directions. The tone will need to go on long enough for any noise in the system to average out relative to the size of the difference that you want to detect. This is addressed (IIUC) by the Fourier uncertainty principle. On the hardware side of things, I'd naively expect modern systems to have very low jitter in both dimensions. However, I fully expect the human side of things is significantly more complicated. An article from 2013 describes research purporting to show that humans exceed the Fourier uncertainty principle (apparently through some sort of nonlinear biological wizardry) by more than ten fold. (https://phys.org/news/2013-02-human-fourier-uncertainty-principle.html https://phys.org/news/2013-02-human-fourier-uncertainty-prin...)