Fundamental frequency discrimination for resolved and unresolved harmonics with the same pitch in the same spectral region

Abstract

To investigate the hypothesis that fundamental frequency (F0) is encoded via different mechanisms for resolved and unresolved harmonics, F0 discrimination was measured for harmonics that had the same pitch and were in the same spectral region, but which differed in resolvability. Summing unresolved harmonics in alternating phase increases their pitch by an octave relative to sine-phase summation; this is not found for resolved harmonics. An alternating-phase, 100-Hz F0 complex tone and a sine-phase, 200-Hz F0 complex tone, both filtered between 1000 and 2000 Hz, have the same pitch. However, the first complex tone contains unresolved harmonics and the second contains resolved harmonics. The experiment measured sequential F0DLs and d’s for two such groups of harmonics that were both resolved, both unresolved, or for which one group was resolved and the other unresolved. Performance was worse for unresolved versus unresolved comparisons than for resolved versus resolved comparisons. More importantly, performance was worse still when the harmonic groups differed in resolvability (resolved versus unresolved). This provides some evidence for the hypothesis that resolved versus unresolved comparisons are impaired by the need to compare the outputs of separate pitch mechanisms. [Work supported by an EPSRC doctoral training grant.]