Paroxysmal atrial tachycardia may be caused by several different things. The fast rate may be triggered by a premature atrial beat that sends an impulse along an abnormal electrical path to the ventricles. Other causes stem from anxiety, stimulants, overactive thyroid, and in some women, the onset of menstruation.
Sudden hearing loss is associated with vertigo in between 20 to 60% of patients (Rambold et al, 2005). The wide spread probably depends on what you define as vertigo -- a little bit of dizziness, or a profound sensation of rotation. Patients with vertigo also usually have worse hearing (Niu et al, 2015).
Sometimes, hypotension, aka low blood pressure can cause dizziness and changes in hearing (ringing in the ears.) Low blood pressure itself isn't a disease, but it is secondary to another condition, which can range from septecimia (systemic blood stream infection caused by an untreated infection somewhere else) to internal bleeding to heart disease ...