案例环境：oracle linux server release 5.7
进入oracle linux系统后，在右上角点击声音图标时，则会弹出如下报错窗口：
the volume control did not find any elements and/or devices to control . this means either that you don't have the right gstreamer plugins installed , or that you don't have a sound card configured .you can remove the volume control from the panel by right-clicking the speaker icon on the panel and selecting "remove from panel" from the menu"
no volume control gstreamer plugins and/or devices found
出现这个错误，有可能是下面几种情况：
1: 用户失去了访问audio设备的权限。
2：相关包package没有安装。
3：服务器本身就没有声卡设备
我碰到的就是这种情况，如下所示，虚拟机（vmware)设置选项。
既然没有声卡设备，那么鼠标指向声音图标，单击右键弹出如下窗口，单击“remove from panel”将声音图标从菜单栏移除。