Binaural Processing Is Key to Tonal-Language Benefits and Right-Ear Advantage for Segregation of Competing Speech

Purpose: This study aimed to compare speech-in-speech recognition between Mandarin-speaking (“Chinese”) and English-speaking (“American”) normal-hearing adult listeners under monaural and binaural listening conditions. Method: Speech recognition thresholds (SRTs) in competing speech were measured in 20 Chinese and 20 American listeners using a modified coordinate response measure task. Target sentences spoken by a male talker were presented alongside two competing sentences spoken by two different male talkers (same-sex maskers) or by two female talkers (different-sex maskers). The target speech was delivered to one ear, while masker speech was presented either to the same ear (“monaural listening”) or simultaneously to both ears (“binaural listening”). Sex-based masking release was defined as the difference in SRTs between same-sex and different-sex maskers. Binaural unmasking was defined as the difference in SRTs between monaural and binaural listening. Results: SRTs were lower with binaural than monaural listening and with different-sex than same-sex maskers. Under binaural conditions, Chinese listeners showed lower SRTs than American listeners (tonal-language benefit), and right-ear targets yielded lower SRTs than left-ear targets (right-ear advantage [REA]). Robust sex-based masking release and binaural unmasking were observed across listeners. Sex-based masking release was greater with monaural than binaural listening, with a significant interaction between language and listening mode. American listeners showed greater release with monaural than with binaural listening relative to Chinese listeners. In contrast, binaural unmasking was larger for Chinese than for American listeners, particularly with same-sex maskers and right-ear targets. Tonal-language benefits emerged only with different-sex maskers, whereas REAs were restricted to same-sex maskers. Conclusion: Significant tonal-language benefits and REAs emerged only under binaural listening conditions, suggesting that binaural processing plays a critical role for segregation of competing speech. Supplemental Material: https://doi.org/10.23641/asha.32137030