as root:

# start ohmd

file '/etc/event.d/ohmd' must exists

also you can check this:

for speakers on:
amixer -qc0 set "Speaker Function" On
amixer -qc0 set "Right DAC_R1 Mixer HP" unmute
amixer -qc0 set "Left DAC_L1 Mixer HP" unmute

for speakers off:
amixer -qc0 set "Speaker Function" Off
amixer -qc0 set "Right DAC_R1 Mixer HP" mute
amixer -qc0 set "Left DAC_L1 Mixer HP" mute

It's no matter if headset / eaphones are plugged in.