NADPH oxidase which constitutively produces superoxide upon formation of a complex with CYBA/p22phox. Plays a role in the biogenesis of otoconia/otolith, which are crystalline structures of the inner ear involved in the perception of gravity. Activated by the ototoxic drug cisplatin. Activated by NOXO1. Cooperatively activated by NCF1 and NCF2 or NOXA1 in a phorbol 12-myristate 13-acetate (PMA)-dependent manner. Inhibited by diphenyleneiodonium chloride. Interacts with and stabilizes CYBA/p22phox. Specifically expressed in inner ear by the spiral glanglion neurons, the vestibular system and the sensory epithelial cell layer of the saccule. Weakly expressed in skull and brain. Expressed in fetal kidney. Mice display balance defects, a tilted position of the head and abnormal performances in motor coordination tests. This is associated with the absence of otoconia in both the utricle and saccule of the inner ear.