iOS 8.4 Ringer volume glitch

The issue is that I could set the ringtone volume level at 50% (keeping change volume with buttons off) and clearly hear the ringtone. But after using it for a day, the volume is discernibly much much lower.

After using the phone and checking this option at the end of the day, the volume is still at 50% of max volume, yet the volume has significantly decreased (almost by a factor of 3 or 4) from what I can perceive. I have recreated this situation to rule out any bias from my perspective and had others hear the comparison as well. I did this by restarting the phone and setting the ringer volume to 50% again, using the phone for about an hour, and returning to the same setting - only to find that the same thing has happened again.

I have never had this issue on 7.1.2, but after updating to 8.4, an insane amount of glitches were discernible. I have since then restored the phone to factory settings and restored from back up. Yet these glitches/bugs are still present. There is no way I can use a phone that cannot properly alert me of incoming notifications.

PS. When adjusting the volume in my sound preferences for my ringtone volume, I can hear distinct static-like sounds as the volume shifts up and down.