Failure of a missing-fundamental complex to interact with masked and unmasked pure tones at its fundamental frequency

Of interest here are the mechanisms underlying the extraction of temporal periodicities from complex acoustic stimuli. Two extreme versions of the underlying mechanisms are examined for possible psychophysical consequences, and experiments of two sorts are reported. In one, the detectability of a 200-Hz tone was measured in the presence, and the absence, of a tonal complex that gives rise to the experience of a missing fundamental having a pitch of 200 Hz in an attempt to see if the missing-fundamental waveform contributes to the masking of the tonal signal. We call this periodicity masking, but were unable to measure any, implying that if periodicity information was being used both to detect the signal and to perceive the missing fundamental, those two streams of afferent information are kept separate by the auditory nervous system, at least initially. In the second set of experiments, an "informational-masking" paradigm was used to introduce high uncertainty about the frequency of the tonal signal, and both detection and frequency discrimination were measured in the presence and absence of a missing-fundamental complex. This time the question was whether the periodicity information in the complex would produce a reduction in the frequency uncertainty about the signal and, thereby, improve performance. We call this possible effect periodicity cueing, but were unable to find evidence for its existence either. The failure to find either periodicity masking or periodicity cueing is discussed in regard to possible organizations of the auditory system, and in regard to the "periodicity-rate gap" seen in primary auditory fibers.