With the background noise the tuner pick this up and makes screeching noises, just like when your cords aren’t plugged in correctly to your amp. You will be trying to tune one cord and it will be thinking your playing another. No matter how close or far away your phone is. Even if you have the settings on the instrument your trying to play and the cords your trying to get tuned. I took my guitar in to the shop and they said my guitar was so off tune from trying to tune it with this app and they even gave it a shot themselves. The app just doesn’t pick up sound and makes tuning impossible. Get a professional grade tuner and save yourself the trouble.