I have connected a tiny piezo pc speaker (https://sktechworks.ca/wp-content/uploads/2017/11/Speaker.jpg) to an arduino and used to tone command to play a simple melody in repeat (square wave only since I didn't use a DAC).
But the speaker is very quiet. I have used a speaker like the green one here:
but it is not siginifcantly louder (I need a piezo either way). I then tried to just connect it to 2 digital ports and just inverted low and high between them, which did make it louder, just not enough.
So here my question, with the same voltage is there a way to produce a louder sound? I just need a sound can clearly hear through a few walls. Because I have a usb speaker (which is 5V) and that one is signifcantly louder.