Voice segregation by difference in fundamental frequency: effect of masker type

Speech reception thresholds were measured for a voice against two different maskers: Either two concurrent voices with the same fundamental frequency (F0) or a harmonic complex with the same long-term excitation pattern and broadband temporal envelope as the masking sentences (speech-modulated buzz). All sources had steady F0s. A difference in F0 of 2 or 8 semitones provided a 5-dB benefit for buzz maskers, whereas it provided a 3- and 8-dB benefit, respectively, for masking sentences. Whether intelligibility of a voice increases abruptly with small ΔF0s or gradually toward larger ΔF0s seems to depend on the nature of the masker.