<<i remember reading in studio sound (about 25 years ago) a review
article of all
the boundary mics. one point that stuck to my mind was that the mic on
cantilever and the mic mounted flush would be theoretically identical
to some
measurable high frequency and the flush mounted mic would be superior
above
this.>>
That's the point with this approach; that up to a certain wavelength-
defined distance from the boundary, the incoming direct sound & the
reflected sound are in phase, & therefore sum constructively, i.e. an
increase of acoustic volume. At the highest frequencies, i.e.
shortest wavelengths, direct & reflected sound will sum out of phase
at an ever decreasing distance from the boundary, causing a loss of
acoustic volume at those frequencies. The frequency at which the
superior response of a flush mounted diaphragm vs one in a cantilever
facing into the boundary is so high I can't imagine it making a
meaningful difference for any real world listening purposes, however I
question the wisdom of having an object (the cantilever) which will
cause an acoustic shadow for the direct sound.
Scott Fraser
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