What group should a new user to be included in in order to use audio device?
 

I have a slackware 14.0 32bit installed.

And I add a new user in addition to the default 'root'. The new user in set in the group 'users'. However, as I log in with KDE as the new user, everything seems fine except that a message is prompted in the system tray of KDE that the audio device cannot play.

I guess it is a problem regarding access right, since I can use the audio normally when logging in as 'root'.

There are a long list of groups. So which group should I assign the new user in to use the audio device?

Add your user to the audio group (pretty obvious, I would think). You may need some more groups, like video, cdrtom, plugdev and netdev.

It works. Because the list of groups is too long, I missed the group of 'audio' when I ran over the list.

I always use 'adduser', it's an interactive script as opposed to 'useradd'. It will ask for additional user group then just hit UP arrow key to get 'audio cdrom floppy plugdev video power netdev lp scanner'.