This app is a great idea, but mine had some issues. It freezes about 20% of the time when I open it, and the sound has stopped playing on the external speaker, although it did when I first bought it. I can use playback via headphones, but that does not work very well for choir, when everyone needs to hear the pitch, and I would rather not have headphones hanging out of my ears during a performance! Any updates coming?
kwasiroman about Pitch Pipe