This experiment determined the pitch of mixed‐polarity pulse trains, high‐pass‐filtered at 2 and 4 kcps. It was found that pitch may be associated with pulse rate at rates higher than the limit of 150 pps found with unfiltered pulses. At frequencies higher than those supporting pulse‐rate pitch, some tendency to hear a pitch equal to the spectral difference frequency appears. Evidence for the difference‐frequency interpretation is the contrast in pitch of patterns equated for pulse number but possessing all‐harmonic and odd‐harmonic spectra. Comparison of the pitch results with a computer simulation of basiliar‐membrane displacements revealed some correlation of difference‐frequency pitch with displacement envelope. It is hypothesized that the high‐pass input‐filter slope combines with the natural‐membrane low‐pass characteristic to form a narrow passband. The envelope of membrane displacement at the passband site tends to contain a pitch‐significant frequency component equal to the difference frequency. It is furthermore suggested that a major source of the pitch of low‐frequency broad‐band periodic sounds is roughly the 400‐cps region of the basilar membrane.