It looks like you are using propagation speed for the 4th argument in plane wave - propogation speed should be the 5th argument. The 4th argument should be carrier frequency.
This brings up another point - the concept of 'carrier frequency' implies the narrowband assumption - i.e. the modulating waveform is much lower frequency than the carrier waveform, which may not apply in the case of sound waves. I recommend looking at the use of the WidebandCollector for acoustic use cases in the following example:
I would recommend trying to see if your MVDR estimator works if you use the WidebandCollector to collect the received waveform.
