Each ear should have vestibular apparatus which consist of saccule, utricle and three semicircular canals. The organ can detect horizontal acceleration, vertical acceleration, and rotational acceleration. Impaired vestibular apparatus will result in losing the sense of balance.
The organ is very sensitive as it was able to detect a small acceleration. That is why most disease in the vestibular apparatus will result in an acute(fast onset) fake perception of acceleration, called vertigo.