[time-nuts] Striking change in iPhone time accuracy with 8.2
n1hac at dartmouth.edu
Wed Apr 1 23:20:19 EDT 2015
There is evidence that the ear can discern differences in timing down to
the uS range. See a discussion by David Blackmer of DBX and Earthworks:
On 4/1/15 7:11 PM, Chris Albertson 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. Apparently clicks are easier to hear.
> The problem we were solving was Determining if two clocks were in sync
> by listening to the ticks.
> I don't think you need two iPhones to experiment with audio
> perception. A computer that can produce stereo audio and a pair of
> headphones would be enough Or a pair of speakers. There is lots of
> good quality audio software, some of it free that allows you to make
> sounds with various delays. My guess is that most people reading this
> already own the required equipment, less the software.
> On Wed, Apr 1, 2015 at 1:50 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>> albertson.chris at gmail.com said:
>>> Sound travels at about 1 foot per ms. So you can effectively delay the click
>>> on one phone my placing it 8 feet farther away then the other phone.
>>> Adjust the distance until the clicks seem to occur at the same time. That
>>> said, I doubt your ears are sensitive enough to work at the single digit ms
>> Your brain uses the difference in arrival times at your ears to determine
>> direction. That works better with high frequency clicks rather than low
>> frequency rumbles. You can work out how good it has to be to get reasonable
>> results, but it's well below 1 ms.
>> The usual test case is to jingle some keys. Sit on a stool with your eyes
>> closed. Have a friend jingle the keys in various locations. Right-left
>> works well. Up-down doesn't work very well.
>> It would be fun to play with a pair of beeping iPhones and see what sort of
>> direction they appear to be coming from. I wonder how much the length of the
>> beep influences things.
>> These are my opinions. I hate spam.
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
More information about the time-nuts