Voice matching in sung duos: Is it related to spectrum envelopes?

Abstract

Choir singers report anecdotally that two voices can be perceived as a good match for each other, or not. Could “matching voices” be explained by the spectrum envelopes? Thirteen singers sang a duo in unison or canon with an adjacent prerecorded reference singer, in a moderately reverberant room. Singers controlled the stimulus timbre, using variable filters in medium and high frequency bands. They were asked to adjust the filters, while singing, for “best” and “worst” perceived matching. The singers then performed the song again, but with the filters automatically set to their chosen (dis-)preferences. The Self-to-Other ratio as a function of frequency [SOR(f)] at the ipsilateral ear of the participant was estimated from multiple microphone signals to predict separately the long-time average spectra of Self and Other. Most participants rated the sound with extreme filter settings at ±15 dB as the “worst” match, while “best” matches were fairly evenly distributed. Some but not all participants preferred the spectra to be complementary. However, at low frequencies, SOR(f) was about +10 dB, and very irregular but rarely negative at medium and high frequencies; so how an adjacent singer can be heard at all will require further investigation.