Music hours per day and volume?

I've had good results playing for a few hours a day but this is only cos my phone goes out with me, I wouldn't see the problem with having it on 24/7 if that's good for your setup. The plants won't technically listen to the music, they'll hear the vibrations so volume really depends on the bass output of your speakers. I use a JBL charge 4 which is very bassy so can have the speaker real low but right next to the pots. I tend to stick to softer music such as piano classical or something along those lines. A test was conducted in India and it was found that Indian classical music boosted yields in Tobacco plants yet Rock music killed the plants within a few days. Maybe something there to influence your choice of genre :). This research is easily found through google should you wish to verify. This link may also help! https://vitesy.com/blog/nature/is-there-a-correlation-between-plant-growth/ Hope this helps!