1. Fort Hays State University
Hays, KS
Speech Intelligibility: Does Stress Play a Role in Detecting
Word Production Differences of Non-native Speakers?
Carol Ellis, Ph.D.
Valerie Van Roeyen, B.A.
Whitney Wietfeld, B.S.
Introduction
• The U.S. is more diverse today than it has ever been in the past.
• Due to increased growth of non-native English speakers within
the U.S. there is an increased growth of speakers trying to
produce understandable English speech (Derwing & Munro,
2005).
• Identifying small differences between word productions of native
and non-native speakers of English may play a part in the
intelligibility of speech.
Purpose
• The purpose of this study was to investigate and document the
role that word stress plays in understanding non-native speakers’
speech.
Methodology
Participants
• Eleven non-native speakers from the Accent Modification class at
Fort Hays State University in Hays, Kansas.
• Six spoke Arabic (males) and five spoke Chinese (one male and
four females). All speakers were between 21-28 years of age.
• Three native English-speaking listeners.
Procedures
• The eleven non-native speakers read a list of twenty multisyllabic
words into a recorder.
• A native English researcher read the same twenty multisyllabic
words into the recorder.
• Each non-native speakers’ words were matched with the
corresponding English researcher’s words.
• The three listeners then listened to the pairs of words and judged
them to be “same” or “different.”
• They were allowed to listen to the pair a second time if needed.
Analyses
• The data obtained from the listeners was tallied by the research
students and grouped for each of the eleven non-native
participants.
• Individual word pairs were grouped into three different
categories depending upon whether one, two or three listener(s)
heard differences between the pairs.
• Data were formally analyzed using PRAAT.
• Data were compared to the actual stress or mispronunciation
differences.
Results
Intelligibility differences were noted for both stress differences and
mispronunciations of words.
• Table 1 shows the number of word pairs that were judged to be the same or
different by listeners based on stress.
• Table 2 shows the number of word pairs that were judged to be the same or
different by listeners based on mispronunciations of words.
Figure 1. Example of acoustic waveform and spectrogram used in the analysis.
Conclusion
• The results of this study provide some evidence that stress used by non-native
speakers does affect their intelligibility, which agrees with a study by Shriberg
and Kwiatkowski (1982).
• These results also provide evidence that mispronunciations of words may also
play an important part in the intelligibility of accented speech, which agrees
with a study by Weston and Shriberg (1992).
Discussion
• Accent modification is a service available for individuals interested in
modifying their accent and its goal is to improve speech intelligibility.
• The results from this study may help identify factors that can be targeted to
help support the intelligibility of non-native speakers.
• The results of this study indicate that stress may be an appropriate target to
teach in an accent modification curriculum.
Limitations and Future Research
• Larger sample size
• More diverse sample size
• More listeners
• Does stress play a bigger role in one language versus another?
• Does vocabulary play a role in how intelligible non-native speakers are?
Selected References
• Behrman, A. (2013, November). How to conduct prosodic training for foreign accent management. Presented at
the American Speech-Language-Hearing Association Convention, Chicago Illinois.
• Chen, S. H., & Wang. Y. R. (1990). Vector quantization of pitch information in Mandarin speech. IEE
Transactions on Communication, 38(9), 1317-1320. doi: 10.1109/26.61370
• Derwing, T. M., & Munro, M. J. (2005). Second language accent and pronunciation teaching: A research-based
appraoch. TESOL Quarterly, 39, 379-397.
• Shriberg, L.D., & Kwiatkowski, J. (1982). Phonological disorders III: A procedure for assessing severity of
involvement. Journal of Speech and Hearing Disorders, 47, 256-270.
• U.S. Census Bureau. (2013). American Community Survey Reports. Washington, D.C: Government Printing
Office. Retrieved from: www.census.gov/acs/Downloads/ACS_Accuracy_of_Data_2011.pdf
• Weston, A.D., & Shriberg, L.D. (1992). Contextual and linguistic correlates of intelligibility in children with
developmental phonological disorders. Journal of Speech and Hearing Research, 35, 1316-1332.
** For a complete list of references please contact Dr. Carol Ellis at cmellis2@fhsu.eduThe authors have no relevant financial or nonfinancial relationship with this study.
Table 1- Listener Judgements Related to Stress Use
Participants’ Decisions by Use of Stress
Decision Type Same Different
Stressed
Correctly
Yes 354 159
No 60 87
Table 2- Listener Judgements Related to Mispronunciation of Words
Participants’ Decisions by Mispronunciation
Decision Type Same Different
Pronounced
Correctly
Yes 47 169
No 367 77