>The speed of sound in a low humidity environment is going to be something like 350 to 400 meters per second. I've heard that humans can't distinguish 10msec from instantaneous. That would be somebody standing about 4 meters away from you making a sound.
Human ear can distinguish about 500 microsecond difference. I.e. a difference in distance of about 20 centimeters. Humans use this for directional hearing.
That's why smallest possible latencies are so important.