[time-nuts] audio-visual perception of time (was: Striking change in iPhone time accuracy with 8.2)

Attila Kinali attila at kinali.ch
Thu Apr 2 06:09:18 EDT 2015

On Wed, 1 Apr 2015 16:11:54 -0700
Chris Albertson <albertson.chris at gmail.com> wrote:

> The key jingle experiment is detecting a phase difference between
> ears.   I was writing about our ability to know if a sound is "in
> time" with some other sound.  For example if a bass player is keeping
> time with a drummer.   I figure we can do that to about 20 ms or maybe
> a little better. 

Actually, quite a lot better. I cannot give you any "hard" numbers
as I dont have my perception psychology books with me and my google
skills fail to locate any good website, but quoting from memory:
You can assume that an average human can perceive audio-visual time
differences down to 3-10ms (flash to click), with a bit training probably
better. Just auditory time differences are quite a bit better, in the
couple 100us range (if you can avoid temporal masking effects).

But, a word of caution here: lot of the performance of the sensory
system depends on the training. Most people do not train neither
hearing nor seeing. They are contempt with flickering TV sets or
movies where audio is delayed by 30-40ms. They do not even perceive
it conciously and ignore it unconciously. But on the other side, if
you have someone who trains them, you can have "interesting" results.
For example ask one of your nices, who play first person shooters a lot,
about the "jerking" special effects in movies.

Anyways.. so much from my side on this OT.

			Attila Kinali

It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson

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