A sound signal added to its repetition after a delay time is able to produce a pitch, repetition pitch, corresponding to 1/delay time. When the repetition is attenuated relative to the original sound, the strength of the pitch sensation (the perceptibility of pitch) decreases. For white noise with its attenuated repetition and for sequences of pulse pairs with each second pulse attenuated, the threshold of perceptibility of pitch has been determined as a function of the pulse-pair interval, the sensation level, the bandpass center frequency and the delay time (pulse interval). The followingconclusions can be drawn-somewhere in the hearing organ, timing information is preserved, rather perfectly, by means of some kind of autocorrelation process. Above a certain minimum sensation level, the perceptibility of pitch is independent of the sensation level. Dependent on the frequency value of the pitch, there is a specific spectral region for which the perceptibility of pitch is at a maximum. The threshold as a function of bandpass center frequency and delay time shows a conformity between the existence region of repetition pitch and the existence region of the tonal residue.