I have a hardware accessing question. For a project, I was wondering if it would be possible to use the smartphone's speaker as a second microphone, similar to the idea that you can plug in a headset into your computer's audio jack and use it as a microphone.
Questions on Android Enthusiasts Stack Exchange are expected to relate to Android within the scope defined by the community. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about reopening questions here.If this question can be reworded to fit the rules in the help center, please edit the question.
Sorry, as far as I am aware, there is no way to do this.
The speaker is highly ingrained into the hardware, and it would be highly difficult to get this to work - never mind that it could be impossible.
It could be possible, but it would require loads of hard work - including rewiring, and possibly some soldering - and your device may not survive.
Proceed at your own risk, but I would say that it isn't possible.