Comment 42 for bug 479296

That's a good question.
I see the pulseaudio messages in the log (the one below is from the latest / current boot), but I see no pulseaudio process in ps when I'm using the machine.
So it seems pulseaudio was active in the machine at boot, 14 seconds after the very first boot-time log message was written, but isn't when I look at it.

The only mention of pulse I find in ps are in ssh-agent, gpg-agent and dbus-launch: All three have been launched with a cmd containing a pulse related option:
--exit-with-session /usr/bin/pulse-session gnome-session