I'm having the same exact issue you're describing. I don't know what the root of the problem is.
I have that too. Usually I'm exercising so I can't re-insert the headphone jack, but if I wait I while I got a very loud crackle sound and then it starts working again.
It's been that way since I got this phone, but I've been working through the more serious bugs first like the camera and wifi not working. This is one buggy phone!