The role of harmonic spectral structure in the cocktail party problem

Abstract

Harmonicity is believed to provide an important acoustic grouping cue underlying sound segregation, though the mechanisms by which this occur, and its importance in real-world conditions, remain unclear. To test the role of harmonicity in the segregation of speech, we used a modified version of the STRAIGHT methodology for speech resynthesis to manipulate the fine-grained spectral structure of otherwise natural-sounding speech tokens. We then measured the ability of human listeners on two tasks: speech comprehension—of individual speech tokens in isolation, of speech in noise, and of speech presented concurrently with other tokens—and detection of a mistuned harmonic. We tested the importance of harmonicity in both tasks by jittering harmonic frequencies up or down by a small amount, rendering the speech inharmonic. We tested the importance of familiar spectral structure by deleting even-numbered harmonics. This latter manipulation left only the odd harmonics, a spectral pattern that, while harmonic, does...