English lexical stress produced by native (L1) Bengali speakers compared to native (L1) English speakers: an acoustic study Shambhu Nath Saha 1 · Shyamal Kumar Das Mandal 1 Received: 21 May 2016 / Accepted: 22 September 2016 / Published online: 3 October 2016 © Springer Science+Business Media New York 2016 Abstract English lexical stress is acoustically related to combination of duration, intensity, fundamental frequency (F 0 ) and vowel quality. Errors in any or all of these cor- relates could interfere with production of the stress contrast, but it is unknown which correlates are most dif- ficult for L1 Bengali speakers to acquire. This study compares the use of these correlates in the production of English lexical stress contrasts by 10 L1 English and 20 L1 Bengali speakers. The results showed that L1 Bengali speakers produced significantly less native like stress pat- terns, although they used all four acoustic correlates to distinguish stressed from unstressed syllables. L1 English speakers reduced vowel duration significantly more in the unstressed vowels compared to L1 Bengali speakers and degree of intensity and F 0 increase in stressed vowels by L1 English speakers was higher than that by L1 Bengali speakers. There were also significant differences in formant patterns across speaker groups, such that L1 Bengali speakers produced English like vowel reduction in certain unstressed syllables, but in other cases, L1 Bengali speakers had tendency to either not reduce or incorrectly reduce vowels in unstressed syllables. The results suggest that L1 Bengali speakers’ production of English lexical stress contrast is influenced by L1 language experience and L1 phonology. Keywords Acoustic cues · Lexical stress · Phonology · Duration · Intensity · Vowel quality · Vowel reduction 1 Introduction English is an international language for communication throughout the world. English is also being studied and spoken as a second language in more countries than ever before. Thus, a comprehensive understanding of the vari- ation present in the dialects of English spoken in the world today is a fundamental issue for the development of Eng- lish language education as well as spoken language science and technology. Asia is home to the largest number of English learners and speakers in the world, and it is important to learn about Asian language speakers’ English and identify their features. In India, combining native (L1) and nonnative (L2) speakers, more people speak or understand English than any other country in the world (Sailaja 2012; Visceglia et al. 2009). Around 4 % of the population of India speaks English fluently (Desai et al. 2010). Thus research on spoken English of Indian speakers is urgently needed. Therefore, it is necessary to collect L2 English speech from as many regions of India as possible and compare with L1 English speech based on segmental and supra segmental aspects in order to derive a set of core properties common to all varieties of English spoken by Indian speakers. As English continues to grow in impor- tance as a language for international communication, L2 English speakers need to produce English language prop- erly. Proper production of English speech involves in the correct production of one of the most important supraseg- mental features—that is lexical stress. Stress is inseparably linked to multiple aspects of the English language such as rhythm, intonation, and pronunciation. It gives the overall & Shambhu Nath Saha shambhuju@gmail.com Shyamal Kumar Das Mandal sdasmandal@cet.iitkgp.ernet.in 1 Centre for Educational Technology, Indian Institute of Technology, Kharagpur, India 123 Int J Speech Technol (2016) 19:827–840 DOI 10.1007/s10772-016-9373-1