Acoustics characteristics of open transition in nonnative consonant cluster production

In cross-language speech production, nonnative consonant clusters are often modified by epenthetic or transitional vocoids. Focusing on English speakers’ productions of nonnative stop-initial clusters (e.g., /bn/, /bd/), the present study identified several acoustic characteristics that distinguish cases of epenthesis from accurate cluster realizations. Both modified and accurate productions contained an open transition between the initial stop and following consonant, but epenthesis transitions had longer durations and other properties indicating greater vocal tract opening. Time course analyses revealed that the acoustic markers of epenthesis were present throughout the transition but became more pronounced following stop burst/frication. The acoustic measures studied here are simple, largely automatic, and provide a means to supplement or replace hand-coding of cluster production accuracy with statistical classification. The combination of semi-automatic measurement and machine learning makes the phonetic study of nonnative cluster production more objective and scalable, and could be extended to the investigation of transitional vocoids more generally.