Non‐technical summary  Cochlear inner hair cells transform acoustic signals into electric signals. Another type of hair cells, outer hair cells, actively amplifies sensory signals and thus contributes to the exquisite sensitivity of the human auditory system. Cochlear amplification is based on length oscillations of outer hair cells that are mediated by a membrane‐bound motor protein, prestin. Prestin transforms electrical signals directly in conformational changes and in extremely fast length changes of outer hair cells. Prestin belongs to a family of proteins that mainly function as anion transporters or channels. We here demonstrate that – under certain anionic conditions – all branches of this family can function as anion channels. These results show that prestin shares important functions with other family members that are not motor proteins. Knowledge of how prestin can switch between motor protein and channel mode will increase our understanding of molecular mechanisms underlying cochlear amplification.