The bilabials /p/, /b/ and /m/

As anyone will know who has studied Latin or who speaks a Romance language, the term ‘bilabial’ comes from bi- (twice, double), and labialis (having to do with the lips). In the pronunciation of English, the three consonant sounds that are made by bringing our lips together are /p/, /b/ and /m/ as in pat, bat and mat, respectively.

/b/ – The Sounds of Speech

Image from The Sounds of Speech ( Sadly, this excellent site is being forced to close because of technical reasons, though it is now available as an app from the App Store and Google Play.

The action of bringing our lips together is natural
. Mammals breastfeed their young, who bring their lips together to draw nourishment, and I wasn’t surprised some time back to discover that in a significant number of quite different languages the word for ‘mother’ begins with or contains the /m/ sound. Similarly, I guess it shouldn’t come as a surprise that these three sounds figure in most of the world’s languages, if not all.

On paper, then, these are sounds that shouldn’t cause too much problem. In practice, life’s not quite so simple. Even a sound as primeval as /m/ has its problems for speakers of English from some first-language backgrounds. It can’t appear at the end of a word in Spanish, for example, so the name ‘Adam’ is often pronounced with a final /n/ in Spanish-accented English. It’s not that Spanish-L1 learners can’t pronounce /m/, but that a deep-seated, subconcious rule transfers across and prevents the automatic pronunciation of /m/ in that final position. Greek-L1 speakers, in contrast, don’t pronounce /m/ before /b/ and so ‘gamble’ will sound like ‘gabble’ [Almost immediately after publishing this post, I learned that this is NOT correct. Please see Daniel Barber’s comment at the end of the post, and my reply to Daniel for the correct description of the problem]. Again, this is not a question of having to show learners how to make /m/. Rather, it’s about creating exercises with vocabulary that targets the /m/+/b/ consonant ‘cobbination’, and so helps students to overcome their first-language habit. Patience is an asset in both cases. Lots of patience.

Where things really get tricky, however, is with /p/ and /b/. Quite often the pedagocical focus with these two consonants is placed on voicing (the vibration of our vocal chords when we speak). /p/ is described as voiceless (i.e. there is no vibration of the vocal chords) and /b/ as voiced (i.e. the vocal chords vibrate as we pronounce the sound). However, the difference between words like pat or bat does not lie in voicing, since when it comes before a stressed syllable, /b/ is only very lightly voiced, or is totally devoiced. The key difference between these two sounds when they come at the beginning of a stressed syllable, and hence the focus of our teaching, lies in the fact that in English /p/ is significantly more strongly aspirated than /b/.

Aspiration is a small puff of air that is released as the lips separate as we finish making /p/ . (Go to Google Images and type in ‘aspiration’ if you need to know more). Though aspiration is the key difference between /p/ and /b/ in English, it is not a distinguishing feature of these sounds in many other languages, including Arabic, French, Greek, Italian, Japanese, Malay, Polish, Portuguese, Russian or Spanish. Learners from these language backgrounds will need our help here.

The finger is also pointed at voicing for the difference between cap and cab. This leads teachers to focus on the voicing of the final /b/, and, although it embarrasses me now to admit to it, I can remember getting my own students to put their thumb and first finger on their throats and feel the voicing in ‘cab’ that was absent from ‘cap’. Unfortunately, final /b/ in English is only weakly voiced (if at all), and so once again, we’re left momentarily wondering how we manage to distinguish between these two sounds when they occur at the ends of words.

The answer lies not in the consonant themselves, but in the preceding vowel, which is shorter before /p/ than it is before /b/. This shortening effect (technically know as fortis clipping), is actually what the ear notices when it has to distinguish between similar pairs of words like cap and cab. The vowel in cab is significantly longer than the vowel in cap, and with learners whose first language is German, Polish or Russian, for example, we need to focus their attention on generating and perfecting this ‘extra’ vowel length rather than artificially voicing the final /b/.

A third, less frequent problem, is the confusion of /b/ with /v/. Spanish and Japanese speakers, for example, come to English with sounds that are neither /b/ nor /v/ but that can be understood as either. This classic pronunciation problem is usually illustrated through the confusion of words like boat and vote or berry and very, and arises because neither Spanish or Japanese have the phoneme /v/, and in its absence speakers from both language backgrounds use /β/, a bilabial sound which not in the pronunciation of English and which is usually heard as /b/ even though it is not the same.

This problem reappears in the opposite direction, however, when /b/ comes between vowels, as in words like habit or global. Here the influence of their first languages causes Spanish and Japanese speakers to use /β/, which this time is frequently heard as /v/, changing the intended word (habit = have it), or creating a nonsense word (globalgloval). Either way, communication is threatened. Something similar happens with Korean speakers of English, whose attempts at /f/, a sound that Korean does not have, can sound like /p/, making coffee sound like copy.

So, this was going to be an easier post. Nothing as abstract or potentially controversial as the two posts on accent. However, when you get past a basic treatment of even seemingly simple sounds, you discover that, as with accent, you’ve entered a bit of a minefield. And a post like this isn’t going to get you out of it, though if the post has served its purpose, it will at least have made you conscious of where you are.

To help you get out safely there are a number of books that have sections dedicated to the problems that learners from specific L1s have with the pronunciation of English. These include:

  1. Teaching the Pronunciation of American English. Peter Avery & Susan Ehrlich. Oxford University Press.
  2. Learner English: A teacher’s guide to interference and other problems. Michael Swan & Bernard Smith. Cambridge University Press.
  3. Teaching the Pronunciation of English as a Lingua Franca. Robin Walker (Yes, that’s me.) Oxford University Press.

You can also find information on the internet but not all of it is reliable because it hasn’t always been edited by a professional. Editors are the bane of any writer’s life, but they do make you check your facts. (Wish I had one here now, in fact!)


6 thoughts on “The bilabials /p/, /b/ and /m/

  1. Hi Robin,
    Aspiration appears in the course book I’m writing with Marek Kiczkowiak at the moment. It’s great to be involved with a phonology curriculum that addresses such interesting and significant features. It’s the first time I’ve seen it in a general English course, and rightly something we’re proud of. But it’s involved a steep learning curve, as there are all sorts of details that complicate the surface rules, and something that I thought worth sharing here.
    As far as I can see the general consensus is that aspiration occurs
    1) only on the unvoiced consonants /p/, /k/ and /t/, so in ‘Pat’ but not in ‘Bat’
    2) in stressed syllables, so in the ‘c’ in ‘Curtain’ but the ‘t’ in ‘curTail’
    3) only when followed by a vowel, e.g. ‘Tend’ /t(h)end/, ‘oCCur’ /əˈk(h)ɜː/, ‘aPPear’ /əˈp(h)ɪəʳ/;
    4) but NOT when part of a cluster, so in ‘Culture’ but not ‘sCulpture’.

    However, I think there can be aspiration in certain clusters, when /p/, /t/ or /k/ are followed by /r/, /l/, /w/, or /j/, e.g. ‘print’, ‘climb’, ‘twenty’, ‘quite’ and ‘queue’. I found one possible explanation here, suggesting it is to do with ‘Voice Onset Time’ (scroll down to first answer):
    As it’s the first time down this rabbit hole, I wonder what your and others’ thoughts are.
    And if I can be your editor for a moment, I do know a little Greek, and the fact is that Greeks DO pronounce /m/ before /b/, as in their word for ‘lamp’, ‘lámba’ (excuse the lack of Greek script, but it is pronounced /’lamba/) The confusion may arise because of orthography. To make a hard /b/ sound at the start of a word you write it as a diphthong ‘mp’ (or the Greek script equivalent); so ‘mp’ reads as ‘b’. However, if this letter combination is in the middle of a word it is pronounced /…mb…/. I don’t think Greeks would have a problem with that sound (but I may be wrong).


  2. Hi Daniel

    Thanks for editing for me. It’s really useful. Immediately I read your comments I went to check out the /m/+/b/ thing about Greek-L1 speakers of English. I was quoting a Greek teacher of English when I made the comment, but have now contrasted what he told me with other sources, and the problem would appear to be the other way around – that /m/ is inserted before /b/ making ‘bubble’ sound like ‘bumble’ (possible confusion), or ‘bible’ sound like ‘bimble’ (confusion due to creation of nonsense word). It just goes to show that you’re only as good as the information you’re given and that it pays to contrast sources (although I normally do do that, as I guess you know).

    With regard aspiration, hopefully it will begin to appear more and more in coursebooks. Apart from yourselves, I know of at least one other major ELT publisher that now has all its authors and content creators working off pronunciation syllabuses that contain aspiration, and at quite early levels, as opposed to it being seen as an ‘advanced feature’.

    And yes, all texts on the phonetics and phonology of English state that aspiration is a property of the voiceless (more correctly ‘fortis’) plosives /p, t, k/. That said, it is weaker in /k/ because of the distance the aspirated air has to travel through the mouth to get out. I discovered this last in class when demonstrating aspiration to my students by getting them to hold their hands in front of their mouths and say ‘pin’, ‘tin’, ‘kin’. The general feeling was that /k/ wasn’t aspirated, which left me looking a but stupid (again).

    You’re also correct when you say that is absent in /sp/, /st/, /sk/ clusters, so there will be none in ‘sport’, ‘stop’ or ‘sky’, for example. And the effect of aspiration with /l, w, r, j/ is for the aspiration (which is fully there) to devoice these otherwise voiced consonant sounds.

    But in terms of pronunciation teaching, perhaps the point I should have made more explicitly in the post is that:
    – transfer of L1 habits from the learner’s L1 is far greater in pronunciation than in other areas of learning English.
    – this transfer will appear in the least expected places, such as in superficially uncomplicated sounds such as the bilabials /p, b, m/.
    – teachers need to be very patient in any treatment of problems generated by transfer, especially with teenagers and adults, who for various reasons can be quite resistant to change in their pronunciation habits.


    • Thanks for clarifying that Robin. I was wondering why the aspiration with /k/ was less noticeable – that makes sense. Great conclusions you make, especially re L1 transfer.


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