12.04 sound keeps auto-muting when idle

Question

I just installed 12.04 on an HP8510W. Everything works fine except for one weird behavior which I have noticed. When ever there is no audio playing, the audio mute indicator on the laptop is on. As soon as I start playing a you tube video the mute indicator turns off and I get sound.

Here is my pulse audio output which says that the sink is suspended because it is idle:

Welcome to PulseAudio! Use "help" for usage information.
list-sinks
1 sink(s) available.
index: 0
    name: <alsa_output.pci-0000_00_1b.0.analog-stereo>
    driver: <module-alsa-card.c>
    flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
    state: SUSPENDED
    suspend cause: IDLE 

I tried running alsamixer, but I don't see the auto-mute option.

Solution

To stop pulseaudio from suspending a sink when idle we may comment out (by adding #) the following line in our default.pa (located in /etc/pulse/, or in ~/.pulse) to look like follows:

 # load-module module-suspend-on-idle

Restart the pulseaudio server to take effect (by running pulseaudio -k in a terminal)