Connecting 50 Microphones on a raspberry pi

Question

I want to create a microphone array like in the image below...

How can I do it for a raspberry device ?

I want the input to be stored for a few seconds on the sd card, and not to have a live stream, if live stream is possible, that would even be better....

would I need a multiplexer, if so, how many ones?

Answer 1

Question

1. How to connect Rpi to 50 microphones?

2. How to store a few seconds of analog audio signal on the SD card?

3. Need a multiplexer? if so, how many?

Short Answer

1. A quick and dirty hobbyist DIY wiring is to connect the 50 microphones to a structured/layered multiplexer/dimultiplexer of analog switches.

2. You can use an Analog To Digital (ADC) chip/module to convert the few seconds of analog signals to a long string/array of digital values, and stored it in SD card.

3. You can use any analog multiplexor/demultiplexor such as HC4351.

Long Answer

/ to continue, ...

References

MCP3008 SPI 8 Channel 10 bit ADC

CD74HC4051-EP Analog Multiplexer and Demultiplexer [Supports Defense and Aerospace Applications] - Texas Instruments

MC74HC4351 Analog Multiplexers/Demultiplexers with Address Latch using High−Performance Silicon−Gate CMOS [Obsolete version, to replace by newer version] - On Semiconductor/Fairchild Semiconductor

Appendices

Appendix A - Analog Mux/Demux Block Diagram

Appendix B- 8 Channel ADC Block Diagram

Appendix C - Mini Microphone and Power Amplifier