Garbled Ringtone and Voicemail Playback

Twice in the last week ringtones and voicemail have played with unrecognizable sounds. It seems like the speed of play is slowed dramatically so that a "ping" sound is playing more like a "fire alarm", not the nice fire alarm, the really nasty one fire trucks use at intersections. In addition the voicemails playback so badly it sounds like machinery and morse code. I have found that cycling power on the phone fixes it, but only temporarily, apparently.

I have only one anecdotal comment which is that my sister tried to call me and before she tried it was OK but then after it wasn't. Here is the dialogue on text.

8:04 - Sis: oops, somehow my phone called you, accident, sorry!

8:06 - Me: huh, didn't hear it ring, but now also my beeps and tones are screwed up

8:06 - Sis: magic powers! Samsung vs. Apple!

8:07 - Me: haha!

8:08 - Sis: There was a wierd message playing when I realized I called you and I listened to see if you were there . . . you weren't.

If I opened "sounds" and tried changing the sounds then they would sound terrible, disturbing my office mates!

Playing back voicemails they were very quiet and electronic sounds in the background.

Any ideas what is wrong?

iPhone 6s no contract on AT&T iOS 9.1

114GB with 82.7Gb available