Reduced cognitive load is potentially associated with the improved intelligibility of Lombard speech in Mandarin-speaking children

The Lombard effect is a widespread and effective mechanism whereby speech intensity is increased and acoustic features are modified to maintain efficient communication in noisy environments. However, its occurrence in children speaking Mandarin, a typical tonal language, has not yet been verified. Moreover, the mechanism underlying the maintenance of communication efficiency in noisy environment of Lombard speech remains insufficiently explored. In this study, we recorded and analyzed the speech intensity and duration of 7–8-year-old children speaking Mandarin under quiet (plain speech) and noisy (Lombard speech) conditions. Heart rate (HR) and skin conductance level (SCL) were also measured during a concurrent memory accuracy test for plain and the Lombard speech using the E-prime. Our results confirmed the presence of the Lombard effect in 7–8-year-old children speaking Mandarin, and showed that Lombard speech elicited higher intelligibility as well as smaller changes in HR and SCL in noise, potentially indicating of lower cognitive load. Therefore, in addition to energetic masking release and linguistic enhancement proposed by previous studies, our present study suggested that reduced cognitive load is potentially associated with the improved intelligibility of Lombard speech in Mandarin-speaking children.