[CurlyDave]

...At the speed of sound (~767 ft/s) that could be...

The 767 number is actually speed of sound in mph. In ft/s the actual speed of sound in air is ~1125 ft/s.

[SteveH]

yeah, woops, haste makes waste, and thanks for pointing out the error. then (i suppose) the secondary audio path would have to be ~1125 ft / 2 = ~562.5 ft longer than the primary audio path.