On 2022-12-04, Fons Adriaensen wrote:
All such schemes with three coincident mics (e.g. three cardiods, an omni and two fig-8, etc.) are equivalent in the sense that there is a simple linear transform from each of them one any other.
Though since two already suffice, the linear transform back to the instantaneous soundfield is overcomplete. As such you can perchance use three microphones to cut back on directional errors, or maybe average out some noise. Presuming your hypercardioid has some higher order directional components instead of just being of just first order, maybe you can utilize the now-trifold symmetry to bring some extra directionality into play. (Cut into TriField, frontally.)
But most likely not. Most likely you'll end up with a compact mic array, with little or any capability above the classical SoundField.
So unless you exclude such trivial processing, and insist on a system with a one-to-one correspondence of mics and speakers, it really doesn't matter which one you use.
Even that one-to-one correspodence wouldn't help, if the microphones are cardioids, hypercardioids, any which way. Because if their directional patterns do not possess characteristics above first orrder, they can be returned back to a first order mic by some linear transformation. They are all equivalent to each other — and where they are not, at first order, they fail the isotropicity POA Ambisonic tries to achieve.
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