The equivalence of acceptable noise level (ANL) with English, Mandarin, and non-semantic speech: a study across the U.S. and Taiwan.

Objective: Acceptable noise level (ANL) determines the maximum noise level that a listener is willing to accept while listening to speech. The objective of this study was to determine the equivalence of ANL measured using different speech stimuli for native speakers who lived in the U.S. and Taiwan.

Design: ANLs were measured using English, Mandarin, and the international speech test signal (ISTS) at each site. The same babble noise was used across speech stimuli. The ANLs were considered equivalent if the difference was unlikely to be greater than 3 dB.

Study Sample: Thirty adults with normal hearing were recruited at each site.

Results: For each site, the equivalence test suggested that the native-language and foreign-language ANLs were equivalent. Between the two sites, ANLs measured using the listener's native language were also equivalent. Although the ISTS ANL obtained within each site was equivalent to, and highly correlated to, the native-language ANL, the data were unable to confirm the equivalence of the ISTS ANLs obtained from the two sites.

Conclusions: The results suggested the possibility of directly comparing ANL measures carried out in different countries using different languages. However, it remains unclear if the ISTS can serve as an international ANL stimulus.