Ingo Molnar wrote:
> so in terms of mouse pointer 'smoothness', it might very well be
> possible for humans to detect a couple of msec delays visually - even
> though they are unable to notice those delays directly. (Isnt there some
> existing research on this?)
With great trepidation, I put on my experimental psychologist
hat and add to this thread from the recent archive...
Bruno Repp at Haskins Labs has done some interesting work
showing that the motor system can respond to timing perturbations
which are below the limit of conscious perception. The
experiments used synchronization tapping, where the person's task is
to tap their finger in synchrony with a sequence of evenly
timed tones (say, 5/second). 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.
This was audition, and vision might be signficantly different, but
it provides some support for Ingo's hypothesis above.
Sorry, I don't have my academic references handy, but the following
is probably one of the relevant publications:
Repp, B. H. (2002b). Automaticity and voluntary control of phase correction
following event onset shifts in sensorimotor synchronization. Journal of
Experimental Psychology: Human Perception and Performance, 28, 410-430.
Back to lurking,
Steve Finney
PS Thanks for all the kernel work!
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
On Tue, 31 May 2005 16:03:55 -0400
Lee Revell <[email protected]> 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.
Hi,
hmm, there must be a misunderstanding here. I did have a soundcard of
which the DA/AD's added another (ca.) 5 ms of latency to the systematic
latency (1.3 ms roundtrip with 32 frames per period at 48khz
samplerate). I could hear the difference between using a periodsize of
64 frames to a periodsize of 32 frames with that card.. 32 frames/period
gave me a total latency of around 6.3 ms. 64 frames/per period resulted
in a total roundtrip latency of 7.7 ms. I could hear that difference. 32
was very well usable, 64 wasn't. It seems my personal borderline for
perceiving "zero latency" was somewhere between 6.3 and 7.7 ms..
Maybe my original post was badly worded. Hope to have cleared it up
(also i'm not sure on the exact value of the additional latency the
AD/DA's introduced. Might also have been 4 or 6 ms.. Something in that
range though)..
Flo
--
Palimm Palimm!
http://affenbande.org/~tapas/
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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