<keybind key="XF86AudioMute">
  <action name="Execute">
    <command>amixer set Master toggle</command>
  </action>
</keybind>
<keybind key="XF86AudioRaiseVolume">
  <action name="Execute">
    <command>amixer set Master 5%+ unmute</command>
  </action>
</keybind>
<keybind key="XF86AudioLowerVolume">
  <action name="Execute">
    <command>amixer set Master 5%- unmute</command>
  </action>
</keybind>