The Nor150 is equipped with a headset socket:
The headset socket is located at the lower left corner of the bottom of the instrument. It is a 3.5 mm jackplug of "TRRS" type (Tip Ring Ring Sleve).
The headset connector is a 3,5 mm minijack of the "TRRS" type.
This type of connection is in use on a lot of mobile modern phones.