One other way to intuitively evaluate the audibility of such random, low frequency jitter if you are into analog sound. Let's look at the measurement of a Linn turntable:
http://www.stereophile.com/content/...power-supply-measurements#bA0gIcPIt6uEPkxt.97
Here an LP with a 1 Khz tone was used as the source signal for the measurement. Again, in an idealized situation we would have a single, super sharp spike at 1 Khz and nothing else.
We clearly do not have that here. There are "shoulders" or skirts around our main 1 Khz tone and that indicates random speed fluctuations or in digital lingo, "jitter." We know they are random because if they were not, they would show up as spikes as I have indicated (deterministic/periodic jitter).
Focusing back on the random, close-in jitter that is the topic of this thread, we see massive amounts of it here. The main 1 Khz tone is broadened even at levels of just -10 db! We have large amounts of it by the time we get to -50 db.
The measurements of jitter we have been showing use source signal of 10,000 Hz, not 1,000 Hz like is used above. The higher the frequency, the more pronounced the level of jitter. It is a simple matter to compensate though.
To have -50 db of jitter, we need to have a timing error of 2 microseconds at 1 Khz! This is 2,000,000 picoseconds!!! Far, far higher cry than 0.5 picoseconds advocated by Mike.
As we all know, there are tons of advocates of LP playback. None complain of their stereo image being smeared even though they suffer from random jitter that is two million times higher than being advocated.
Why is that case? Reasons we have mentioned before: threshold of hearing and masking. Without these two psychoacoustic effects, no one would be able to enjoy analog formats. They have horrendous timing errors yet with good content, they are delightful to listen to. And even more so for their advocates who consider it better than digital.
The levels in analog jitter can be so high that we can just analyze them in time domain where the actual level of sound can noticeably change. More on this in another post.