My question is, whether i can connect multiple isd1820 to one speaker (in parallel) without damaging the modules.
What if i ensure with diodes that current flows only towards the speaker?
To mix audio signals you need a mixer so you'd need a mixer followed by an amplifier that's going to drive the speaker (since the existing amplifiers are going to the mixer instead of to the speaker. You can make a simple passive mixer with resistors but you still need to follow it with an amplifier.
So all I'd have to do is connect the outputs using a 5k (right value?) resistor each to an amplifier (like lm386) and then I'm good?
I do my best, but I'm obviously not a native speaker.
Honestly, I don't really know what it's good for. I found it on several sites