Comment 10 for bug 1268880

I have this problem as well with the newest 14.04 daily build.

Laptop:
Lenovo T410

OS:
Description: Ubuntu Trusty Tahr (development branch)
Release: 14.04
Codename: trusty

Kernel:
3.13.0-19-generic #40-Ubuntu SMP Mon Mar 24 02:36:06 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

-> acpi_listen gives NO output if I press mic mute

-> xev gives:
KeyPress event, serial 38, synthetic NO, window 0x3e00001,
    root 0x84, subw 0x0, time 1702753, (-362,419), root:(360,471),
    state 0x10, keycode 156 (keysym 0x1008ff41, XF86Launch1), same_screen YES,
    XLookupString gives 0 bytes:
    XmbLookupString gives 0 bytes:
    XFilterEvent returns: False

KeyRelease event, serial 38, synthetic NO, window 0x3e00001,
    root 0x84, subw 0x0, time 1702753, (-362,419), root:(360,471),
    state 0x10, keycode 156 (keysym 0x1008ff41, XF86Launch1), same_screen YES,
    XLookupString gives 0 bytes:
    XFilterEvent returns: False