Intense noise exposure causes hearing loss by inducing degeneration of spiral ganglia neurites that innervate cochlear hair cells...Here, we describe a strategy to increase cochlear NAD+ levels in mice by administering nicotinamide riboside (NR), a recently described NAD+ precursor. We find that administration of NR, even after noise exposure, prevents noise-induced hearing loss (NIHL) and spiral ganglia neurite degeneration. These effects are mediated by the NAD+-dependent mitochondrial sirtuin, SIRT3, since SIRT3-overexpressing mice are resistant to NIHL and SIRT3 deletion abrogates the protective effects of NR and expression of NAD+ biosynthetic enzymes. These findings reveal that administration of NR activates a NAD+-SIRT3 pathway that reduces neurite degeneration caused by noise exposure.