On Sat, Jul 23, 2011 at 09:35:41PM +0100, dave.mal...@york.ac.uk wrote: > I have an interesting question (well, I think it's interesting). The > Soundfield microphone, like any directional microphone, has a boosted > bass response to close sounds. When listening to this through a speaker > rig, we hear this boost and tend to interpret it as meaning the sound is > close especially in a dry acoustic with a Greene-Lee head brace etc., > etc.,. However, surely (unless I am being more dense than usual tonight) > this is a learnt response based on the behaviour we have heard from > directional mics? After all, taken individually, at those sort of > frequencies our ears are essentially omnidirectional and not subject to > bass boost (to anything like the same degree).
The individual capsules are directional and hence will show the bass boost for a close source. Each of them is the sum of an omni and a figure-of-eight in some ratio, assume for a moment that this ratio is independent of frequency. Now if you combine them to form W, the fist order components are made to cancel out, this means there is no bass boost in W (a tiny amount remains in practice since the mics are never at exactly the same distance from a source). Conversely, our ears may be omnidirectional at LF, but using two of them to 'measure' the gradient (which is what we do implicitly - there is no other directional info at LF) would mean that the bass boost is introduced anyway: it is a property of the near field of a source, not of the receiver(s). Ciao, -- FA _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
