如何安装alsa-base和pulseaudio？
我有一个声音问题，声音设置显示“虚拟输出”，这意味着它没有读取我的声卡。
我按照这里的说明，进入“备用”方法，运行“sudo apt-get remove –purge alsa-base pulseaudio”，但“sudo apt-get install alsa-base pulseaudio”向我显示：
Reading package lists... Done Building dependency tree Reading state information... Done Package pulseaudio is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source Package alsa-base is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'alsa-base' has no installation candidate E: Package 'pulseaudio' has no installation candidate 不，我甚至没有声音图标。 我该如何安装这两个包？
将以下行添加到我的源列表允许我安装这些包：
deb http://cz.archive.ubuntu.com/ubuntu raring main
可以在packages.ubuntu.com上找到更大的镜像列表
返回音频符号并进行设置，但我的“虚拟输出”问题仍然存在。