Psychophysical evidence of the harmonic cancellation process and its relationship to pitch sensitivity and voice segregation

Harmonic cancellation is a putative mechanism in the auditory system that might contribute to the perception of the fundamental frequency (F0) of a complex tone and to the segregation of voices by their F0. This study aimed to provide more tangible evidence of its existence, acting like a comb-filter. Experiment 1 measured a masked detection threshold (MDT) for a narrow noise band target against harmonic or inharmonic complex maskers. The target center frequency either coincided with a harmonic position or fell in between harmonics. MDTs were lower with harmonic than inharmonic maskers, but this difference was lost when the target approached one of the harmonic positions, allowing precise capture of the width and benefit of the comb-filter in 99 listeners. Notably, the benefit was larger around 1000 Hz than 400 or 2600 Hz, while the width increased slightly at higher frequency. In the same participants, experiment 2 measured the F0 difference limen (DL) and experiment 3 measured speech reception threshold (SRT) for a monotonized voice against complex tones with F0 differences of 0, 0.25, 0.5, 1, and 2 semitones. Associations between the three tasks suggested that individuals with a refined comb-filter had better F0 DL and overall lower SRTs.