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The fact that tone complexes with missing fundamentals can be perceived to have a pitch that is below their lowest frequency component can have counterintuitive consequences.
Consider the tone sequence shown in the spectrogram here:
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Pitch is determined in most cases by the periodicity of the sound waveform. However, some sounds have other, more subtle periodicities. In some cases, these periodicities may determine the pitch, but in other cases they don't. Here such subtle periodicity is illustrated - the periodicity of the envelope.
This sound illustrates one of the sounds used in the study of Cariani and Delgutte (1996) on the coding of pitch in auditory nerve fibers. It is a so-called single-formant vowel, since its spectral envelope has a single peak in frequency (vowels have multiple such 'formants' - see Chapter 4). See Fig. 3-9 in the book.
Here are two consecutive periods, one pair taken from the beginning (green) and one pair from the middle (orange) of the sound:
Here are examples of three sounds that evoke pitch without being strictly periodic. A detailed discussion of these sounds can be found in the pitch chapter of the book.
Each of these sounds is approximately periodic, and their spectra have an approximately periodic structure, reminiscent of the strictly harmonic structure of periodic sounds. In each case, there is a clear period. If the sound is shifted by that period, it best resembles its unshifted version.