Could the Duo officials make it possible to toggle audio exercises (turn them on or off, like speaking exercise)?
You can. Go to settings, and pick “speaker/off.” I often turn mine off when I am not working with headphones.
This is true but I wish that that option didn't turn all the sounds off. I guess it doesn't matter (unless I'm too lazy to toggle it again), but I always feel weird when I get home and start a lesson and the lady isn't automatically talking to me anymore, and there's no sound effects. Still prefer to leave it off since practicing at college without headphones can be a hassle though... :)