Hair cells are specialized receptors necessary for detecting sound, head rotation, and gravity. They are located in the inner ear. Hair cells are killed by many agents including loud sounds, certain therapeutically useful drugs (e.g., aminoglycoside antibiotics and anti-cancer drugs), infections, defective gene expression, and aging. Hair cell loss in humans is currently irreversible and leads to permanent deafness and debilitating balance dysfunctions. Birds, in contrast to humans (and rodents) robustly replace damaged and lost hair cells, a process called “hair cell regeneration”. This research group's focus was identifying ways to induce hair cell regeneration in mature mammalian inner ears, using a wide variety of methods and preparations to better understand the inner ear, its development, and its potential repair.