I have tested three 7mic array, they have the same problem.
The 7mic array with the original or any other XVSM firmware cannot record voice using one channel on Raspberry PI, but they works well on other system, like Ubuntu. for example:
arecord -d 3 test.wav
so we have to specify 2 or more channels to record voice on Raspberry PI:
arecord -c 2 -d 3 test.wav
BTW, the 7mic array with RAW firmware works well on any condition.
Others users found this issue while they were using arecord to record, but work normally when using python. Actually, data of two channel in xvsm firmware are all same.
I have tested three 7mic array, they have the same problem. The 7mic array with the original or any other XVSM firmware cannot record voice using one channel on Raspberry PI, but they works well on other system, like Ubuntu. for example: arecord -d 3 test.wav so we have to specify 2 or more channels to record voice on Raspberry PI: arecord -c 2 -d 3 test.wav
BTW, the 7mic array with RAW firmware works well on any condition.