linux下麦克风不工作

我这里麦克风的症状如之前声卡output的一样, 不报错但是不工作（偶尔好像也报错）。
弄了好几次不见起色。
今天偶然又看看了alsa网站里的详细安装说明，发现我这里设备文件的权限没设对。
于是运行chmod a+rw /dev/dsp /dev/mixer /dev/sequencer，之后问题解决（我这里没有midi)
不过似乎噪声很大，尚待解决。但是好歹可以用了。

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