Q. I have two QS8s in the rear corners of my room. Iâ€™m confused by the speaker setup menu in my Yammi RXV 1300 receiver. When it asks how many feet away for the QS8 surround speakers, is it asking the distance from the mains, or how many feet away from my listening position? I believe this deals with speaker delay? How is this done? â€” Dan
A. The Yamaha speaker setup menu is asking you the distance in feet between your listening position and the QS8 surrounds. The reason you must set this correctly involves compensation for a peculiarity of human hearing–our tendency to locate a close-up sound before one thatâ€™s a little farther away.
The receiver digitizes all the incoming signals for each channel and inserts an appropriate degree of digital speaker delay so that the sounds radiated by the two surround channels reach your ears after the sound from the center channel and the main speakers. Since in many installations, the surround speakers will be closer to the listening area than the main front speakers or center channel, our ears would normally detect the sound from the surround speakers before that from the main speakers, which would totally throw off the illusion. So by entering the distance from your chair to the surround speakers, the Yamaha inserts enough digital delay so you will hear the sound from the main front speakers first, then that from the surround speakers. (Sound travels at about 1 foot per millisecond, so itâ€™s easy for a digital circuit to apply the appropriate amount of delay.)
Itâ€™s a kind of precedence effect thatâ€™s important in real life because it helps protect and alert us to nearby events that might be threatening. (If a car horn beeps to your right as you step off a curb, you immediately glance there and take steps to avoid being run over.) But with multi-channel surround sound, the illusion only works if the sounds from nearby surround speakers reach your ears after the sound from the main front speakers.