Interaction of Rate of Speech and Accent on Comprehensibility

Natacha Moreno, M.S., CCC-SLP


Accents can be a joy to listen to, while at other times they can lead to effortful listening and frustration.  A listener’s perception of accent can depend on factors such as the speaker’s degree of accent, the listening conditions, and the complexity of the words being used. 

Functional magnetic resonance imaging (fMRI) is now routinely being used to study how the brain processes accented speech.  In a 2014, researchers Han-Gyol Yi, Rajka Smiljanic and Bharath Chandrasekaran, observed the neural processing of native English speakers as they listened to native American English, and Korean-accented English sentences.  Results of their study showed that “foreign-accented speech perception places greater demand on the neural systems underlying speech perception.” (Yi, Han-Gyol, and Rajka Smiljanic, 2014).


These increased processing demands while listening to heavily accented speech can interfere with attention, language, and memory and ultimately the listener’s comprehension, or ability to interpret and understand the speaker’s intended message. In 2010, researchers Erin Wilson and Tammie Spaulding examined the effect of speech intelligibility on listener comprehension and processing time of Korean-accented English.  Results of their study showed that the time required to process speech increases as a function of decreasing speech intelligibility (greater accentedness). 


Because of the additional time required to process heavily accented speech, researchers have begun to explore whether the rate of speech of the accented speaker can affect comprehension of the spoken message.  In a study published in 2014, researchers  Matsuura, Chiba, Mahoney, and Rilling examined whether a slower speech rate enhances listening comprehension.  Participants included 179 Japanese university students who were studying English as a foreign language in Japan.  Speech samples included Indian English (a less familiar accent to the participants) and North American English (a more familiar accent).  Participants listened to the speech samples on two separate occasions - first at the original speech rate and then, several weeks later, at a reduced rate.   Significantly higher mean comprehension scores were achieved with the slowed speech rate when listening to the heavily accented speakers.  There was no significant speech rate effect observed in the comprehension of the less accented speakers.


The outcome of this study has important implications for optimizing verbal communication between foreign-accented speakers and native listeners. A slowed rate of speech is recommended to allow the listener additional processing time, and as a result, improved comprehension of the verbal message.



Matsuura, Hiroko, Reiko Chiba, Sean Mahoney, and Sarah Rilling. "Accent and Speech Rate Effects in English as a Lingua Franca." ResearchGate. Research Gate, 01 Oct. 2014. Web. 13 Mar. 2015.


Wilson, E. O., & Spaulding, T. J. (2010). Effects of noise and speech intelligibility on listener comprehension and processing time of Korean-accented English. Journal of Speech, Language, and Hearing Research, 53, 1543–1554.


Yi, Han-Gyol, and Rajka Smiljanic. "The Neural Processing of Foreign-accented Speech and Its Relationship to Listener Bias." Frontiers. Frontiers in Human Neuroscience, 08 Oct. 2014. Web. 19 Dec. 2014.