Twice lately, my normal alarm sound has been replaced by a single repeating mellow tone. It is not a sound that can be found in the list of alarm sounds in my clock app. When it happened this morning I noticed that my phone was down to around 10% battery and the battery saver notification was showing (I didn't notice if this was the case the previous time). I wondered if this is connected and is normal android behavior. Is my phone playing a simple tone alarm rather than the normal tune because it is low on charge?