Answer:
Hearing static equilibrium
Explanation:
Hearing Static equilibrium is the sense which interprets the position of the head permitting the Central Nervous System to maintain stability and posture when the head and body are not moving.
Vibrations dynamic equilibrium is the special sense which interprets balance when one is moving (or at least the head is)
Therefore, when you are sitting motionless, the sensation is related to the hearing static equilibrium.