The cochlear length virtually describes the length of the cochlea in a straight line. Sever-al theoretical options for measuring the length of the cochlea are conceivable. In choosing the type of cochlear implant elec-trode, this can play a crucial role. A wide range of electrodes is available, especially among the models designed to preserve re-sidual hearing and structural integrity. It is believed that the depth of cochlear implant electrode insertion has an influence on the functional hearing based on the area of the cochlea that is electrically stimulated.