I leave you here a video where you can hear what a guitar with a side sound hole sounds like. It is an accessory that is not yet widespread but that I consider to be a great success.
Whenever I see how someone reacts when they play a guitar with a side soundhole for the first time, I confirm this.
At approximately the 50th second, the mouth on the side opens and you can see the difference. It is always better to listen to it with good speakers or good headphones. I hope you like it.
Emmanuel Carlucci