# What is the smallest difference in note lengths that an average listener can still perceive?

Approximately speaking, what is the smallest temporal difference, expressed in milliseconds, in note lengths (for consecutively sounded notes) that an average, untrained listener can still (semi)consciously perceive? What order of magnitude are we talking about here? 10 ms? Or more like 50 ms?

In order to make the question a bit easier to answer, let us confine our attention to the following situation: a diatonic scale of quarter notes, played slightly legato on a concert grand, in a slow adagio-like tempo (60 BPM), and in a room without any noticeable reverb.

I'm trying to quantify the "infinitesimal" lengthening and shortening of notes going from one phrase to the next, but I find it difficult to come up with realistic numbers.

Edit: I'm not asking for the shortest perceivable note duration, but for the smallest perceivable difference in length between two consecutive notes.

• I think the OP is going after stuff that's more like "How much shorter can a note be than the one immediately before it before we notice that the notes sound rushed". The edit is definitely leaning in that direction. – Dekkadeci Jul 29 '18 at 6:59
• It's not the length of the notes I think you want to ask about, I think you want ask what the smallest perceivable change in tempo is, which is more about changing the spacing of when the notes start, not how long they are. If you're really asking about how much music can speed up or slow down before listeners notice, please edit or comment confirming that. – Todd Wilcox Jul 31 '18 at 18:21
• If we are talking about a series of changes then a slow accelerando would fit the bill and might give us a fairly low answer. If we are talking about just two notes of different lengths then it might be harder to observe – JimM Aug 12 '18 at 11:38