I have noticed my N9 have different volume of changed ~2 weeks ago - it was somehow low, but currently it is just perfect, and even I have to keep not to the max to be in tune with my preferences.
I think I got the moment when this change occurred - the phone was close to me, running out of battery juice, in power saver mode, then a sms, followed be email came but the notification sounds the phone made were somehow awkward and distorted, lasted longer then they should. After that when I charged the phone overnight the first call received next day - the sound was very loud and I was surprised. So was the next and so on. From that day I had to move the ringing volume down to notches from max.
I know this sounds a little crazy, but I think - can some changes occur to pulseaudio? O ALSA?
I have experienced such changes 1-2 times before, after phone reboot I have loud and clear sound, until the next reboot pushes it back to quiet again.
Anybody with similar observations?