After install the unity-settings-daemon_14.04.0+14.04.20151012-0ubuntu1_amd64.deb on a lenovo machine, reboot, then test the microphone mute hotkey, the OSD icon is correct (now it is microphone icon, then it is speaker icon) now.
So the unity-settings-daemon_14.04.0+14.04.20151012-0ubuntu1_amd64.deb fixed the problem on trusty.
After install the unity-settings- daemon_ 14.04.0+ 14.04.20151012- 0ubuntu1_ amd64.deb on a lenovo machine, reboot, then test the microphone mute hotkey, the OSD icon is correct (now it is microphone icon, then it is speaker icon) now.
So the unity-settings- daemon_ 14.04.0+ 14.04.20151012- 0ubuntu1_ amd64.deb fixed the problem on trusty.