LXDE Volume Keybinding

Add the following lines to ~/.config/openbox/lxde-rc.xml:

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

Issue command => openbox --restart