Subjective tinnitus is the perception of sound without an external acoustic source and represents one of the most common and refractory otologic disorders. This chapter elucidates the complex mechanisms underlying its pathogenesis. Historically linked to hearing loss, tinnitus is now understood to involve significant central nervous system plasticity—a concept formalized in the neurophysiological model. This model posits that while peripheral auditory deafferentation acts as a trigger, the chronic perception of tinnitus arises from maladaptive neural remodeling in the central auditory pathways, including processes like excitation-inhibition imbalance, altered lateral inhibition, and neuronal synchronization. The model also emphasizes the critical role of nonauditory systems, particularly the limbic system, in the chronicization and emotional distress associated with tinnitus. Expanding on this, the integrated regulation theory introduces a tinnitus control system, comprising a central gate-control mechanism and the Eustachian tube ventilation system, which determines whether aberrant neural signals are ultimately perceived as tinnitus. The chapter further explores a range of physiological and psychological risk factors that can influence this system, such as age, insomnia, migraine, hormonal changes, and mental health disorders like anxiety and depression. Understanding these multifaceted interactions is crucial for developing effective, individualized therapeutic strategies.