So this has been happening for the past couple of months. When listening in my car using Bluetooth on my iPhone, the volume drastically changes between songs. Enough to where it will be too quiet to here or loud enough to hurt when it changes. This will often happen during single album that I know doesn't have these volume fluctuations while listening on other devices. I have the audio normalization turned on, but it hasn't made a difference. I'm not using other apps while this happens.