Ubuntu 12.10 crackling and popping sound [duplicate]
A possible solution is disabling "auto-mute" in alsamixer. It is used when the "switch-to-headphone-and-back-again" bug occurs (in high volumes mainly).
First, open your terminal, or press:
CTRL + ALT + T
Then, type and hit "enter":
$ alsamixer
This screen will show up:
Use the right arrow until you select "Auto-Mute"
Then, press the down arrow to set it do "Disable" (see the text above it).
That's it.