Electronic – Connecting sensor microphone CM-01B to Raspberry Pi

No, this is not possible. The main problem is that the audio sample clocks between the four microphones will not be phase-aligned and possibly not match in frequency. Because of this you won't know how to align the four data streams to do proper processing.

It would be better to get a single 4-channel audio USB interface. At least then you'll know that they are all time aligned and sync'd. You can find many of these types of devices at Sweetwater Sound and Guitar Center.

An amplifier... amplifies. Takes a tiny signal, and beefs it up with more voltage / current / power.
A speaker needs that power, to make a coil move in a magnetic field. Attached to the coil is the cone, this displaces air when the coil moves - and we get sound.

A speaker WILL act as a microphone. It's just not very efficient.

If you get real close, and shout really loud, you will get a mediocre signal. In theory, this get passed back to the input where, since we are reducing signal strength along the way, we would have a microscopic signal.

Then comes the final hurdle: recording this signal.

Computer data, in the form of ones and zeroes, gets chewed through a chip called Digital-Analog-Converter [DAC] before being sent to that amplifier. To record our eensy signal, we need an Analog-Digital-Converter [ADC].

ADC's are weird and wonderful beasts. Your computer has one - it's what the "mic" input goes to. No matter how you quibble about passing signals backwards through an amplifier, I fail to see how you get a digital version without adding your own hardware [ie. planting a bug].