Voltage-gated L-type Cav1.3 calcium channels comprising CACNA1D:CACNA2D2:CACNB2 open in response to depolarization of the inner hair cell (IHC) caused by an influx of cations (calcium and potassium) through mechanoelectrical transduction (MET) channels in the apical stereocilia (inferred from mouse homologs). The calcium channels are located on the basolateral surface of the IHCs in close proximity to cytoplasmic ribbon structures that temporarily anchor and cluster glutamate vesicles near the inner face of the plasma membrane (inferred from mouse homologs). The proximity between the Cav1.3 calcium channels and the ribbon structures allows a small number (about 10) of calcium channels to produce high localized concentrations of Ca2+ near the site of glutamate release (inferred from mouse homologs).