Past measurements and observations appear to give equivocal evidence on whether waves of different frequency travel down the cochlea at the same rate. If different frequencies travel at different rates, then steady-state waveforms will show changes in addition to those attributable to relative amplitude change of the components. Sinusoids of simple (octave) ratio were fed into guinea-pig cochleas, and the waveforms were observed with paired electrodes at two well-separated points. Comparative phase shifts for the two components indicate that, on the stapes side of a given observation point along the membrane, all frequencies lower than the frequency of maximum amplitude for that point travel at the same rate.