In general, we want
Crossover frequency
is normally set near the lower limit of
stereo perception, which we are taking to be around 80 Hz
(§2.12 on page
).
Crossover frequency
is chosen to be the lowest frequency at
which the lowest octave of the HOP is adequately sampled, following
the analysis of §2 on page
. For the five-band HOP example, it is
Hz (§4.7 on page
). From a spatial sampling point of view,
depends on listening geometry, particularly the stage-width,
minimum-source-distance, and listener-distance from the array.
The setting for the upper limit
can be based on how much
high-frequency spatialization is desired. For older
listeners,31 the top row
is normally inaudible in arrays such as the previous example and in
the five-band HOP examples above, such as
Fig.13 on page
. Therefore, the top row can either be simply
omitted for older listeners, or, as a compromise preserving at least
the presence of the high end for the occasional younger listener,
replaced by conventional stereo tweeters (two-channel VBAP), or any
number of tweeters in an undersampled VBAP row, or coaxial mounts
along any lower row. Also, at such high frequencies, wavelengths are
so small that left-right processing is noncoherent, so that
left-or-right ``presence'' is the only available cue for perception.
Thus, an undersampled top row should work quite well for those who can
hear it at all. Finally, much auditory direction perception research
ignores frequencies above 10 kHz.
http://arxiv.org/abs/1911.07575
.