Effects of steady background noise on benefits from voice pitch differences in a “Cocktail Party” environment

Voice pitch is an important cue for auditory object segregation in a multi-talker environment. A recent study showed that the ability to segregate and identify speech based on voice pitch differences is highly correlated with the breadth of binaural pitch fusion, the perceptual integration of dichotic stimuli that evoke different pitches across ears [Oh et al., ASA (2018)]. The goal of this study was to investigate effects of steady background noise on binaural pitch fusion and speech perception abilities in background noise consisting of multiple talkers. Subjects were tested in both quiet and various “soft” audible noise levels (15, 5, and -5 dB SNR) inboth ears with the following experiments. First, binaural pitch fusion measurements were conducted using pure tones. Second, speech on speech masking performance was measured as the threshold target-to-masker ratio needed to understand a target talker in the presence of either same- or different-gender masker talkers. The results showed that both breadth of binaural pitch fusion was minimized and voice pitch difference benefit in multi-talker conditions was maximized at an optimal amount of the noise levels, which is called suprathreshold stochastic resonance effects. A strong negative correlation was also observed between voice gender benefit and breadth of binaural fusion. The findings suggest potential rehabilitation approaches, such as low-level noise, to sharpen binaural pitch fusion and improve related speech perception ability in multi-talker listening environments.