On 5/10/12 11:36 AM, Hal Murray wrote:
albertson.ch...@gmail.com said:
I've alway have thought that if nanosecond level jitter is "bad" then
breathing while listening must be really bad. If you inhale the path length
from your ear to the speaker changes at the microsecond level.
You'd think the resulting doppler shift would drive these audiophiles nuts.
All that pitch shifting.
Perhaps the spectrum of the "jitter" matters. If the frequency is low
enough, I call it wander rather than jitter. Audio doesn't need DC or low
frequencies so wander is easy to filter out with a simple high-pass filter.
Heartbeats may be more interesting than breathing. Does anybody know of
spectrum domain data? It should be possible to collect position info while
also monitoring heartbeat and chest diameter and then crunch some numbers do
see how much of the position correlates with heartbeat vs breathing and then
plot each part in the frequency domain.
oddly, I happen to have just that data to hand, having been looking at
ballistocardiography. If you put someone in a bed, suspended by 4 wires
(one at each corner), your heart beat results in about 1mm displacement
(head to foot). 1 degree phase shift at 1 kHz, or thereabouts.
in terms of displacement in general, breathing is on the order of 1cm
(at 0.1 Hz) and heartbeat is on the order of 0.1-1mm, depending on where
you look. (look up "microwave cardiography" for instance)
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