I’m pretty new to room evaluation / correction, but I do have some knowledge of microphones and Apple devices. Apple will surprise you sometimes with how good some of its consumer stuff is, but I’d be a little skeptical about trusting the iPad’s internal microphone and that app to do very serious room evaluation. You might be able to learn some things and make some adjustments, and if so, I’d love to hear about it. If you check out this topic in this area of the forum, it might be a good introduction to several options now available for more serious room measurement, diagnosis, and treatment.