Why is unmute not working with amixer command?

from this post Arvydas write :

For some reason, muting works fine, but unmuting or toggle has no effect. Upon further investigation I noticed that by muting Master channel, “PCM” and “Master Mono” channels are muted too. Unmuting Master does not unmute those two channels.

That work for me on ubuntu 14.04 (qtile WM) to unmute :

pactl set-sink-mute 0 0

to mute:

pactl set-sink-mute 0 1

Updated:

There a lot of reports on this issue Bug #1026331 and Bug #878986 in launchpad , if you mute/toggle master:

amixer set Master mute

Other channels(Headphone and Speaker in my case) will mute also. but if you unmute/toggle Master :

amixer set Master unmute

the Other Channels will stay mute , but if you try unmute Headphone and Speaker channels sound will come back

amixer set Master unmute
amixer set Headphone unmute
amixer set Speaker unmute

xdotool can be troublesome sometimes, fortunately PulseAudio now provides commands for volume regulation and mute.

try this command: pactl set-sink-mute 0 toggle to toggle mute.

Source: https://wiki.archlinux.org/index.php/PulseAudio#Keyboard_volume_control

I have discover the "xdotool" to simulate media keys. It's simple, because is the same code to toggle mute:

xdotool key XF86AudioMute

And it show the visual notification...

So for further uses of "xdotool":

https://askubuntu.com/questions/235126/simulate-media-keys-in-terminal