Comment 50 for bug 381201

I had this problem, but I managed to fix it by a rather different approach than the workarounds already posted here. I have an HP Pavilion dv9830 laptop, and noticed that the light in my keyboard media strip's mute button would turn from blue (supposed to indicate not-muted) to orange (supposed to indicate muted) about 15 seconds after the last sound has played. The next sound played after that would turn the light blue again, but would also make a loud "pop" sound when the light changes, and I'd notice the first half-second or so of the sound would be clipped off. Now, although this mute button light works as it should in Windows, it has never worked properly in Ubuntu. In fact, if I mute the sound either through the button or through the speaker icon in my notifications area, the sound mutes, but the light stays blue. This leads me to believe that the light turning orange in Ubuntu is actually indicating that the sound card is being powered off.

So, I went into /etc/pulse/default.pa, found the following line:

 load-module module-suspend-on-idle

and commented it out. I then restarted Pulseaudio (killall -9 pulseaudio, and let it respawn), and now the light stays blue, and there's no more popping or clicking when a sample is played.

I don't think the popping/clicking when the sound card is being woken up is a bug. At least, it's not a software bug, and it's nothing that Ubuntu can control or fix. It is a hardware issue caused by powering up the sound circuitry. Therefore, I believe the best way to resolve this issue is not to remove the powersave feature, as it can be an important feature for netbooks and laptops. Rather, the way to resolve this issue is to add an option to PA Prefs to enable or disable Powersave mode and to set the delay time; and have this option disabled by default.