For a number of years, we have investigated auditory function with physiological and psychological measures and with electronic models. We have come to the conclusion that the auditory system must carry out its analysis in the dimension of time rather than the dimension of frequency. There is a simple relationship between frequency and time in signals composed of pure tones and simple combinations of sinusoids, so when these signals are used to test the auditory system the results may be interpreted as indicative of either time or frequency analysis. In complex stimuli composed of transients, such as speech signals, the simple relationship between frequency and time no longer exists. The auditory response to these signals can only be meaningfully interpreted in the dimension of time. Information in the primary auditory neurons is encoded inPulse Density Modulation, a form not used by current engineering technology. The auditory system appears to be an analyzer ideally designed for processing brief transients.