It's common for both acoustic trauma and for those with more physical aspects. So many things could be cause that can also relate to brain processing or just brain processing. It's impossible to find a list or discussion for all reasons unless pulsatile tinnitus has involvement. On the lists from gathering are cranial nerves 9, 10 and 11. The 11th being most prominent of the cranial nerves. Muscles - sternocleidomastoid and trapezius may be weak and influence the 11th cranial nerve. Vascular insufficiency, posture position, jaw-nerves/muscles, teeth, soft palate, throat, sinus, any of the many facial complexes, ear wax. Meniere's.
Much less - Jugular vein or jugular foramen syndrome, carotid artery, Horner's syndrome, Wallenberg's small vessel syndromes, endolymphatic hydrops, idiopathic intracranial hypertension, intrathoracic goiter with hyperthyroidism, thyroid, superior vena cana syndrome, Sigmoid sinus diverticulum, vestibular schwannoma, infection and steroid withdrawals. Other arteries including the vertebral artery.