Solution: Ubuntu 10.04 switched to the root user and there was no sound solution

In ubuntu 10.04, pulseaudio is used by default to manage audio devices. pulseaudio is not allowed to run under the root user, which may cause security problems. Therefore, the system volume cannot be changed, and the voice preference is always "waiting for the sound system to respond ".
If you run pulseaudio directly, you will be prompted.

Root @ alex-MS-7236 :~ # Pulseaudio
W: Main. C: the script should not be run as root.Program(Unless-system is specified ).

If the system parameter is added, many modules are disabled.

There are many solutions. For security reasons, you can install the gnome ALSA mix to manage the volume, but the system still cannot hear the sound. The second is to modify the default pulse configuration file so that it can run under the root permission.
Edit/etc/default/pulseaudio

Root @ alex-MS-7236 :~ # Gedit/etc/default/pulseaudio

Modify the following two items:

Pulseaudio_system_start = 1
Disallow_module_loading = 0

Change to 1 and 0, indicating that the system environment is allowed and the module can be dynamically loaded.
This will have some negative effects. You can read the comments in this document carefully.