Re: Human tIming perception (was: RT patch)

[Richard B. Johnson]

On Tue, 31 May 2005, Lee Revell wrote:

> On Tue, 2005-05-31 at 12:59 -0400, Steve Finney wrote:
> > It takes (IIRC) about a 10 ms or
> > so difference in the sounded sequence
> > for someone to be able to report that there's been a change, but
> > a cnange in the timing of the person's finger movements occurs
> > (_immediately_) at perturbations smaller than 10 ms. That is, there
> > appears to be some dissociation  between conscious perception and
> > perceptual/motor behavior.
>
> Any decent guitar player who has used their computer as an effects unit
> could tell you this.  I can easily perceive the difference between 1.3
> and 2.6, and 2.6 and 5ms latencies.  And there's at least one person
> (also a guitarist, who I have added to the cc:) who swears he cam
> perceive the difference between 0.6 and 1.3ms.  Soundcard ADCs typically
> add 1.5ms latency in each direction, so the actual floor seems to be
> around 3-5ms.
>
> Lee

Well MIDI runs at 31,250 bits/second or 3,906 bytes per second.
After much research by Dave Smith in the early 80s, the MIDI
spec was published in 1983. The data-rate was based upon not
being able to hear the difference in the simultaneity of a
6-note chord (a triad with both hands on the piano). That
equates to 1/3906 * 6 = 0.00154 seconds. (1.54 ms).

Note that because only one note start or stop can sent at a
time, this information was essential for sending and receiving
chords.

Cheers,
Dick Johnson
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