Thanks for the information. But here is my question in more precise form: Suppose you do a recording with ORTF(which of course has its own set of problems). Suppose you record a source that is say 15 degrees left of center. and that the source is a pistol shot(an impulse). Now the impulse will arrive at the left mike before it arrives at the right mike. The time difference is the same more or less as it would be for a dummy head recording since the distance between the mikes is the same (more or less) as the distance between the listeners ears(or the dummy head ears). On playback, the impulse will also arrive at the left ear the same amount of time before the right ear-- as far as the high frequencies are concerned. Namely they are heavily shadowed by the head so that the arrival at the left ear first is blocked from the right ear, and the right ear hears only the right speaker. This is in the highs.
Below around 700 Hz, Blumlein would have put the phase shifts right and that part of time would be there. But the head shadowed part , the high frequency part, is right for ORTF but wrong for Blumlein-- the direct arrival of the high frequency part of the impulse as recorded in Blumlein is simultaneous in the two speakers(as is everything) but there is no reconstruction via head effect because the head effect is essentially total shadowing. Of course there is some head shadowing in the real world, too. But 15 degrees off to one side is not enough to block the highs so completely as 45 degrees (or 30 degrees). So there is some range of angles where the timing is off because of the greater shadowing(almost complete) from the wide speaker separation is not representing the real situation. Is this wrong? This is not my private theory. I think Blumlein was aware of this, and I known other people have mentioned it. Maybe is does not really matter, but it seems real enough. (I believe it is known that time delays in the high frequencies play a role in location) Robert _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
