A new auditory phenomenon was identified in the acoustic impulse response of the human ear. Using a signal averaging technique, a study was made of the response of the closed external acoustic meatus to acoustic impulses near to the threshold of audibility. Particular attention was paid to the waveform of the response at post excitation times in excess of 5 ms. No previous worker appeared to have extended observations into this region. The response observed after about 5 ms was not a simple extension of the initial response attributable to the middle ear. The oscillatory response decay time constant changed from approximately 1 ms to over 12 ms at about this time. The slowly decaying response component was present in all normal ears tested, but was not present in ears with cochlear deafness. This component of the response appeared to have its origin in some nonlinear mechanism probably located in the cochlea, responding mechanically to auditory stimulation, and dependent upon the normal functioning of the cochlea transduction process. A cochlear reflection hypothesis received some support from these results.