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Stuttering in Bilinguals: What We Know

The relationship between stuttering, bilingualism, and second language learning.

Even though stuttering in bilinguals has a relatively long research history, there are still many questions that cause debate: Do bilinguals stutter in just one language or in all of their languages? Is stuttering severity affected by language proficiency? Does one stutter differently in structurally different languages? Does language dominance have an impact on stuttering? And so on. Dr. Valerie Lim, a speech-language therapist in Singapore, has kindly agreed to answer some of these questions for us. She is a recognized stuttering specialist who has successfully treated bilinguals who stutter. What better person to tell us about a topic that is still being researched actively. We thank her wholeheartedly.

Do we know if there are proportionally more bilinguals who stutter than monolinguals?

There are currently no studies that provide information about whether there are proportionally more bilinguals who stutter than monolinguals. The impression some of us have that this might be the case, although unfounded as of today, is related to the fact that the number of bilinguals has grown worldwide.

Do bilinguals usually stutter in just one of their languages or in all of them?

Stuttering is considered to be a motor speech disorder. So it is not surprising that there is more evidence to show that bilinguals stutter in both, or all of their, languages. If stuttering only occurs in one language (i.e., language-specific stuttering), it is probably an exception and related to a significant imbalance in proficiency in each language.

For the majority who stutter in all their languages, is the type of stuttering and its severity dependent upon the language acquired first?

There is still a debate as to whether stuttering manifests itself similarly or differently in both languages. However, there is more evidence to substantiate that stuttering occurs “differently” across languages. In John Van Borsel’s review of the literature, bilinguals who stutter in both languages have been reported to exhibit several kinds of profiles. For example, some have shown a difference in stuttering frequency (number of stutters) across languages, but not the location of the stutters (e.g., within the sentence). Others have shown a difference in stuttering frequency, type and location across the two languages.

What about the role of language proficiency?

The different manifestations of stuttering across languages have been attributed to language proficiency. While some studies have reported that adults show a greater degree of stuttering in the more proficient language, it is more common to find increased stuttering in the less proficient language. But this has to be confirmed with additional data.

The manifestation of stuttering in bilingual children may be different and will be dependent on factors such as the age of the child and his/her stage of language development.

In a study you published in 2008, you showed clearly that language dominance influences the severity of the stuttering. Can you tell us about it?

In our study, we investigated the influence of language dominance (see here) on the severity and type of stuttering in English-Mandarin bilinguals who stutter. Our 30 English–Mandarin stutterers were put into one of three groups: English-dominant, Mandarin-dominant, and balanced bilinguals.

We found that both the English-dominant and Mandarin-dominant bilinguals exhibited higher stuttering frequency in their less dominant language. On the other hand, the frequency scores for the balanced bilinguals were similar across languages.

Did these bilinguals stutter in the same way in their languages even though the languages are very different?

Interestingly, we found no difference in the types of stutters between English and Mandarin for any bilingual group.

Based on our results, we concluded that language dominance seemed to affect the frequency of stuttering but not the type of stuttering behavior. This means that speech-language pathologists should assess all the bilingual's languages, if possible, in order to obtain a clear diagnostic.

When young monolingual stutterers start learning and using a second language, does their stuttering increase in frequency and/or severity?

It is common for stuttering to increase when children (monolingual or bilingual) start putting words together, or when they start producing longer or more complex sentences.

For monolingual children who stutter and who are also learning a second language, the appearance of stuttering in the second language will depend on their level of proficiency in that language, and/or how often they use it. For example, if a child is only able to speak a few words of the second language, it is typical for parents to report no stuttering in that language. However, when the child gains proficiency in the second language, or when he/she starts joining more words together or uses the language more often, parents do notice an increase in stuttering.

For parents of young bilingual stutterers, are there any strategies they can adopt to help their children learn and maintain their languages?

Based on what we know from the literature, there is no evidence to support the notion that bilingual families should only focus on using one language to avoid stuttering. We encourage parents to continue to use both languages in daily life.

We often show parents how to provide language modeling (i.e. how to produce appropriate sentence structure and vocabulary in each language), and how to support the child when he/she is trying to join words or say a sentence. We start stuttering treatment as soon as we deem it clinically necessary for the child and the family.

Concerning speech therapy, should it take place early?

There is strong evidence that early intervention for monolingual childhood stuttering is highly effective if the treatment is done before 6 to 7 years of age (see Professor Mark Onslow’s work presented in the references below). This is no different for bilingual children who stutter. Treatment for older bilingual children and adults who stutter can also help to reduce the stuttering.

Should therapy be done in all of the bilingual's languages or in only one of them?

Research has shown that the treatment for bilinguals who stutter is effective whether or not it is conducted in one language or in both languages. When the treatment is delivered in one language only, we know from the literature that treatment effects can generalize from the treated to the non-treated language.

Similarly, when the treatment is conducted in two languages, stuttering can be reduced in both languages whether or not the treatment is delivered simultaneously (both languages are treated at the same time) or consecutively (one language is treated first and the other language is treated later).

The decision regarding the delivery of treatment for bilinguals who stutter will be made by the clinician who will take into consideration the evidence as well as the individual needs of the child and family. Important factors will be the frequency and type of stuttering, the child's language background, the impact of stuttering on the child and family, the age of the child, and so on.

For a full list of "Life as a bilingual" blog posts by content area, see here.


Valerie P. C. Lim, Michelle Lincoln, Yiong Huak Chan, and Mark Onslow (2008). Stuttering in English-Mandarin bilingual speakers: The influence of language dominance on stuttering severity. Journal of Speech, Language, and Hearing Research, 51, 1522-1537.

Mark Onslow (2018). Stuttering and its treatment: Eleven Lectures. Australian Stuttering Research Centre, The University of Sydney.

John Van Borsel (2011). Review of research on the relationship between bilingualism and stuttering. In P. Howell & J. Van Borsel (Eds.), Multilingual Aspects of Fluency Disorders (pp. 247-270). Bristol, UK: MPG Books Group.

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