Ringer Volume Goes From High To Low

[myhollowworld2]

I'm running a stock rom (Sprint). And with any custom ringtones that I've made using MP3 trimmer, it starts ringing at full volume for a few seconds, goes to low, back to high, and low and so on, until I pick up. I've just did a hard reset last night, due to unrelated issues, but it this persists. Is this normal, and I'm just the only one who doesn't know it? My setting is on vibrate and ring, not sure if this has anything to do with it as I've never changed to see. Any help would be appreciated.