Tinnitus. Tinnitus is experiencing the sensation of sound that is not physically there. Most forms of tinnitus (ringing in the ear) is very common and not concerning. But when the sound is a pulsing sensation or if it is just on one side it should then be checked by an ENT (it could represent abnormal blood flow associated with different benign tumors) - although this is not common, it must be ruled out.
Usually nothing. A humming in the ear(s) is called tinnitus and most often is of no serious consequence. The most recent research suggests that the sound arises from synchronous discharge of electrical stimuli from the temporal cortex (side of the brain). However, if the sound is associated with a hearing loss or balance problem, you must seek consultation with an ENT specialist.