OK. I'm 13 yrs old atm, about 4 ft 11. I've tried another audio sample like this, had it on loop on my phone overnight for about 2 months now; the other day my friend said,"I swear over like the past 2 months you've grown like-" and showed about an inch. So I'm pretty confident these work, but I've heard that after a while they stop working and you have to get a different beat cause your brain's trained or something. So with this one, how much growth can I expect with another 2 months?