Recently, all notification sounds (text messages, etc) are gone and replaced with vibration. The ringer still works. The speakerphone still works. More curious still, if I go to settings->sound-> Default notification sound, clicking on the various sounds makes no sound. IIRC, it's supposed to preview the sound, like it does for ringer. I scanned the forums and I didn't see anybody having this particular set of problems. I've tried disabling the agent/assist apps, tried rebooting, no good.