Goniometric biofeedback is a signal transducer for joint angles during voluntary movement and range of motion adjustment. It can replace the electromyographic biofeedback, when it is impossible or hard to monitor or isolate the muscle.

The international literature has shown studies on goniometric biofeedback effectiveness in controlling knee hyperextension of hemiplegic patients, in postural head control training and joint recovery of elbow, wrist, foot and knee.
The device is lightweight (500 g), easy-to-use, no potentiometer and electrical box needed. It comprises two plastic (plexiglas), mutually constrained, revolving arms. One arm has a magnet, the other has a handle with a magnetic detector that can trigger an audio alarm.

The angle position to be detected by an acoustic signal is determined by the handle magnetic detector. This is always on once it overlaps the magnet on the other arm.
The goniometric device's arms are mounted on the body segments with elastic Velcro straps, and they must be placed sideways to the mechanical axes of these segments.
The device rotation center matches the joint rotation center.