The term ‘comprehensibility’ isn’t part of our everyday ELT vocabulary. We’re more used to talking about comprehension in terms of the questions accompanying a reading or listening text we are working on with our students. But ‘comprehensibility’ is a term used in pronunciation that is related to accent and also to intelligibility, and which, together with these other two, has been the centre of some very interesting research over the past 40 years or so.

The first researcher to use the term ‘comprehensibility’ was Larry Smith (1992), as he tried to disentangle the results of work he had done earlier in order to measure the intelligibility of different native and nonnative speaker Englishes. This search for where intelligibility lay in English is central to what we do today as teachers, and I’ll come back to it when we get to the letter ‘i’ in a few weeks’ time.

What Smith saw from his work was that ‘understanding’ was too general a term to cover something as complex as (un)successful verbal exchange between two people. So to be able to move forward in his investigations he proposed a three-tier system in order to accommodate the different levels of the understanding of a message. For the most elementary level, involving the basic recognition of the words in a message, Smith proposed the notion of ‘intelligibility’. Next came ‘comprehensibility’, the focus of this post, and the demonstration by the listener of having comprehended the meaning of the words in the message in their context. Last in Smith’s system came the concept of  ‘interpretability’, which referred to the listener’s understanding of the speaker’s intention.  For example, if a speaker says ‘It’s a bit warm in here.’, this will have been intelligible if the listener understands bit and not beat, or warm and not worm, and so on, and comprehensible if the listener has understood that the speaker is indicating that the temperature in the room is too high. Lastly, the utterance will have been correctly interpreted if the listener offers to do something to bring the temperature down.

Smith’s comprehensibility and interpretability get quite a long way from where we intervene through the teaching of pronunciation. Perhaps because of this, or perhaps simply driven by the need to better understand the role of pronunciation in spoken English, Canadian researchers Tracy Derwing and Murray Munro set up their own three-way construct involving ‘intelligibility’, ‘comprehensibility’, and ‘accentedness’. They defined intelligibility in essentially the same way as Smith and Nelson, i.e. as the extent to which a listener actually understands what has been said.

Of Derwing and Munro’s other two concepts, accentedness was an attempt to measure how strong the listener perceived the speaker’s (foreign) accent to be. I briefly discussed how accent is the distance between the speaker’s pronunciation and the listener’s expectations in ‘A’ is for accent (2). Lastly, there is comprehensibility, which is the same term used by Smith and Nelson, but which Derwing and Munro use in order to refer to a listener’s perception of how difficult it is to understand the speaker’s words. Same term, different meanings, slightly confusing. ELT!

Intelligibility, Comprehensibility, and Accentedness. Derwing & Munro (2005)

In a review of work on intelligibility up to 2010, Nelson is quite critical of Derwing and Munro’s ‘re-definition’ of comprehensibility (Nelson 2011: 72–74). This is not the place to go into the details of why Nelson found Derwing & Munro’s use of the term ‘comprehensibility’ inadequate, and I think it was necessary to create some sort of term to cover an experience we must all have had. I’m referring to the situation where a speaker is intelligible (i.e. we understand their words), but listening to them and understanding what they  are saying requires a serious effort on our behalf. This is what Derwing and Munro attempt to gauge through their use of ‘comprehensibility’.

Why should we worry about the notion of comprehensibility? Isn’t it enough if somebody is intelligible?

Well no, unfortunately, it’s sometimes not enough. Unless the speaker is someone who is truly important to you, or you have to understand the speaker in some life-threatening situation, for example, all too often if the effort required of the listener is too great, then they get tired and their attention wanders, or, worse still, they switch off and stop listening. At this point, communication has broken down despite the speaker being intelligible.

In addition, a number of international exam rating scales such as IELTS and Trinity College London’s ISE refer directly to the effort required of the listener, that is to comprehensibility. Whether we agree with this choice or not, we clearly need to take it into account if we are preparing students for these exams. (The depth of the raters understanding of the difference between intelligibility and comprehensibility is another matter, but more of that in a later post.)

IELTS Band 9

Trinity College London, ISE II

Comprehensibility as defined by Derwing and Munro is related to accent, which we looked at in my first two blog posts, which you can read here and here. It is also related to intelligibility, which in some ways is the ‘grandaddy’ of them all. But as I said earlier, you going to have to wait a while for a post on that. Another six weeks, in fact. However, if you want to browse the presentation I gave on intelligibility at TESOL-SPAIN back in March this year, you can get a peak at what I’m going to comment here.



Derwing, T. M., & Munro, M. J. (2005). Second. Language Accent and Pronunciation Teaching: A Research-Based Approach. TESOL-Quarterly. 39/3: 379–397.

Nelson, C. L. (2011). Intelligibility on World Englishes. New York: Routledge.

Smith, L. E. 1992.  ‘Spread of English and issues of intelligibility’ in B. B. Kachru (ed.) The Other Tongue. English Across Cultures. 2nd edn. Urbana, IL.: University of Illinois Press.

6 thoughts on “Comprehensibility

  1. Thanks for the post. Over the years I’ve come to see Smith’s framework as largely stemming from a ‘message transference’ model of communication (the speaker ‘codes’ the message and sends it to the listener, who ‘decodes’ it). This so-called ‘conduit metaphor’ of communication has increasingly been seen as inadequate in recent years. There is also the methodological and epistemological problem of our not being able to know what ‘intentions’ and ‘understandings’ are, except indirectly. Munro & colleagues’ framework is more realistic and workable, I think.

  2. Hi Androcles
    Thanks for your comment. Actually, I suspect from what you say that you know more about Smith’s framework than me. But even if Smith’s model is now seen as inadequate, I have a lot of respect for the work he did. His first serious examination of intelligibility in different Englishes dates back to 1979 and was pioneering research in my opinion, not just because of the logistical nightmare it meant for them in those distant, pre-digital days, but also because of the conclusions Smith drew about the non-privileged position of native speakers when it comes to intelligibility in a world where English has become a global tool. It’s over 40 years since Smith drew this conclusion!

    But as you would see from the post, Derwing and Munro are possibly more relevant to pronunciation teaching because of how they re-define comprehensibility, and also because their three terms feel more ‘real’ to ELT practitioners. Certainly that’s been my experience in courses I’ve run on teaching pronunciation.

  3. Thanks for a really interesting post Robin.
    There’s little that I can add other than you may need to be careful about using public version rating scales of some high stakes international examinations because the descriptors that examiners use contain more information. Owing to confidentiality clauses I’m afraid I cannot be more specific. I look forward to seeing ‘i’.

  4. Hi James
    I imagine that most teachers involved in exam preparation have guessed or have been told directly that the scales made public are not identical to those used by the raters, and that these will never be public. But what is made public is a statement of intentions, even if you have to read between the lines to understand what is being said, as is the case with the references to comprehensibility. And that’s what’s behind these blog posts to an extent – helping us to see what is behind different terms or what is being said when these terms aren’t used explicitly.

  5. Just wanted to say that I’m really enjoying this series of posts, Robin. Keep up the good work!

    If I may throw my 2 cents into the mix, what bothers me in many studies on intelligibility or/and comprehensibility is that it’s often ‘native speakers’ judging ‘non-native speakers’. This just reflects the native speakerist idea that pronunciation needs to be comprehensible or/and intelligible to a ‘native speaker’. But of course in a world where English is mostly used by ‘non-native speakers’, whether someone’s pronunciation is intelligible and/or comprehensible is of much lesser importance.

    What I’d like to see more are studies where people from different countries judge intelligibility and/or comprehensibility of different accents. I’ve found very few studies like that, especially large scale ones. If you know any, please let me know.

    • Thanks Marek. Joanne Rajadurai criticised intelligibility studies precisely because the judges were so often NSs. Things are changing slowly, but the ‘presence’ of the NS norm is not going to disappear overnight just because the research invites NNSs to be judges. The very act of inviting people to participate in these studies could easily have the effect of placing the NS norm back centre stage unless care is taken in how the work is done.

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