Minimal pairs for English RP: lists by John Higgins

What are minimal pairs?

Minimal pairs are pairs of words whose pronunciation differs at only one segment, such as sheep and ship or lice and rice. They are often used in listening tests and pronunciation exercises. Theoretically it is the existence of minimal pairs which enables linguists to build up the phoneme inventory for a language or dialect, though the process is not without difficulty.

Each cell in the tables above is a link to a list of minimal pairs derived from a dictionary. Use the tables of vowels and consonants to retrieve the relevant lists. Some of the consonant lists are still in a rather raw state, while all the vowel lists and some of the consonant lists have been edited and commented on. The first versions of the lists included only one pair for each pronunciation, such as heal/hole. Newly revised versions are being added which include all the pairs which arise when one or both members of the pair have a homophone, so giving a better indication of how much confusion a given pair may cause. In the case of heal/hole the new version of the list would include all of the following:

• heal hole
  •   heals holes
  •   healed holed
  •   healing holing
• heel hole
  •   heels holes
  •   heeled holed
  •   heeling holing
• heal whole
  •   heals wholes
• heel whole
  •   heels wholes

Please note that, as you move the mouse over a link, the name of the relevant document should appear at the bottom of the browser window and this gives a further indication of which sound contrast is featured in the list.

How minimal is minimal?

Although the normal definition of a minimal pair specifies that the words differ in one segment, it allows that segment to be widely different in terms of articulation. Another tighter definition of a minimal pair might be words which differ by only one feature. In that case the ideal minimal pair might be cheer versus jeer which differ only in voicing. These two words also belong to the same part of speech and so have the same inflections. Moreover they belong in the same domain of discourse, and are therefore highly confusable. If you were to overhear a fragment of conversation which included:

You should have heard them  ??eering at the end of the game.

They can also be the source of genuine confusions and disputes. A story which appeared in newspapers in April 1998 suggested that the urn known as The Ashes and presented to the winning team in the England versus Australia cricket series contains not the remains of a bail, as the traditional account stated, but of a veil. Another story, involving not strictly a minimal pair but a highly confusable pair of words, appeared in January 1997. It told how a Japanese tourist with a ticket for Turkey had gone to Paddington station in London and asked for directions. She was put on the train to Torquay (a seaside town in South West England). There are all sorts of confusable sentences which can easily lead to 'slips of the ear' among English speakers, such as "the Dutch are suspicious" being misheard as "the Duchess is vicious". The only siginificant difference in the sound of those two sentences is /p/ versus /v/ and this is one which is notoriously difficult for foreign learners and can lead to unexpected problems. On a radio discussion on 13 March 2007 concerning the portrait of Adam Smith on the newly issued £20 note, a speaker with a strong Indian accent said what was first understood as "Adam Smith made a stink about society in a new way." What he really said was "Adam Smith made us think about society in a new way." Another slip of the ear I encountered recently was postcard for coastguard; although the initial /p/ versus /k/ distinction is a fairly strong one, the /k/ versus /g/ distinction in the middle of the word is neutralised by the presence of the /s/. (A contributory factor is that coastguards are often located in picturesque seaside towns, from which it would be reasonable to send a postcard.) A similar misunderstanding arose in conversation between raingear and reindeer. On a recent radio programme a presenter with a noticeable Irish accent was heard to be announcing an interview with "the born doctor Sir Roger Moore", though what he meant was "the Bond actor Sir Roger Moore".

Homophones engender many spelling mistakes; probably the commonest of all is to write there instead of their or vice versa. Sometimes a set of near homophones leads to a spelling error, as in a notice seen recently: RUGBY, STIRLING VERSES LIVERPOOL. In the same way minimal pairs engender many spelling errors in the writing of foreign learners. Among those I have seen recently are "a reach man" (rich man) and "a brought road" (broad road). An Arabic-speaking student once wrote an essay for me about a visit to London during which he had seen "the Pig Pen Watch" (Big Ben). Even national newspapers are not immune. The Times of Tuesday, September 5th, 2000, printed the following:

Apology
Readers will have been surprised yesterday to see the famous Cold War phrase "mutually assured destruction" (MAD) rendered as "neutrally assured destruction" (NAD). What began as a copytaking error somehow survived into this column. To anyone who was confused as well as to those who were not, we offer our apologies.

Source of the lists: Roger Mitton and The Advanced Learners' Dictionary

Hal Gleason (1955, p. 19), writing about minimal pairs before the era of widespread computing, said "Presumably by diligent search through the total vocabulary, minimal pairs might be found for all English consonant phonemes. But there is no guarantee that all will be found, and in any case it is hardly a feasible procedure."

I have not tried to search the total vocabulary, but I have tried to search a vocabulary which includes most of the words available in non-specialist contexts to everyday users of English. In putting together these lists I have used Roger Mitton's machine-readable version of the 1974 edition of the Advanced Learners Dictionary, incorporating Mitton's 1990 additions to the word list (see Mitton 1996). The minimal pair lists below have been prepared from the dictionary by means of a program which sorts the pronunciation field, identifies identical pairs (homophones), substitutes dummy characters for the symbols of the minimal pair, and then flags all the additional homophone pairs created by the process. This generates (fairly) complete lists of minimal pairs, though a certain amount of rather tedious post-editing is needed.

The dictionary lists just over 70,000 words, corresponding to about 40,000 headwords. This may seem rather short, leaving out words which may enter minimal pairs, making the lists incomplete. That is not necessarily a disadvantage. Sometimes, as with a spelling checker, one does not want obscure words included. There exists, for instance, an English word flong. It is the name of a rubberised cardboard or plastic which used to form an intermediate stage of the printing of newspapers on a rotary press. Perhaps it still does. I doubt whether one native-speaker in a thousand knows the word; the only reason I do is that our next-door neighbour in my childhood worked as a printer for a national newspaper and used to give us discarded sheets of the stuff to insulate our hen-house, and I enjoyed trying to read the news stories on it in mirror-writing. But if the Mitton dictionary included the word flong, there would be new pairs fling/flong, flung/flong, flop/flong, flog/flong and flock/flong, which would be of little relevance to teachers or learners.

Semantic loading and density

When this project (collecting and editing minimal pair lists for all the 510 theoretically possible contrasts) is complete, I hope to be in a position to measure the functional load of a pronunciation error, ie how much potential for confusion is created by a particular vowel or consonant error and therefore how important it is. Naturally this is not just a matter of counting the number of pairs, but also depends on other factors. One of these is the part of speech of the words and therefore their potential for appearing in the same contexts. Two nouns, such as beer and pier, are much more confusable than a noun and a preposition, such as frog and from. For this reason the edited lists draw a distinction between the number of pairs and number of semantic contrasts realised by the pairs, and calculate a "semantic loading" figure. Thus if there were 100 pairs but they belonged to only 70 different pairs of headwords, the semantic loading would be 70%. For the longer lists the semantic loding tends to fall within the range 48% to 60%, but the very short lists involving rare sounds are often higher. Paradoxically, the lower the semantic loading, the more confusable pairs may exist for that contrast, since a smaller number shows there are many inflected forms in the list and signals a large number of words in the open classes: noun, verb or adjective. To some extent the figure is arbitrarily dependent on editorial decisions. I have, for instance, treated agent nouns as separate headwords from their verb roots, since there is often a large shift of meaning, as in wait/waiter.

It is also important to take into account the density of the minimal pair, namely how the actual total relates to the theoretically possible number if every word containing one of the sounds were matched by a word containing the other. This would show how the distribution of minimal pairs relates to the overall phoneme frequencies in the same dictionary. A 100% match could only occur if there were exactly the same number of words with each sound in the language, and that is clearly unlikely. But, if the number is unequal, the density depends on which sound you start with. There are 37,729 words in the dictionary containing the vowel /ɪ/ and only 784 containing the diphthong /ɔɪ/. There are 62 minimal pairs. For the diphthong this is a density of 7.9%, but for the monophthong the density is only 0.16%. For an average of diphthong plus monophthong it is 0.32% (calculated using the harmonic mean, of course). What I have decided to do is report the mean density, pointing out where, as in this case, there is a large discrepancy in frequency.

The O'Connor conjecture

A language can tolerate quite a lot of homophones provided they do not get in each other’s way, that is provided they are not likely to occur in the same contexts. This may be a grammatical matter: if the homophones are different parts of speech they are not likely to turn up in the same place in a sentence … If they are the same part of speech, e.g. site sight; pear, pair they can be tolerated unless they occur in the same area of meaning and in association with a similar set of other words. Site may be ambiguous in It’s a nice site, though a wider context will usually make the choice plain. … If homophones do interfere with each other the language may react by getting rid of one or by modifying one.

Problems

There are a number of problems waiting to be resolved:

• Can there be a minimal pair contrast between a vowel and a consonant? Theory would suggest not, since vowels and consonants have different functions in syllable structure. However, one can find pairs such as screen/serene which appear to contrast /k/ and /ə/, but then the syllable count and stress pattern seem to make such pairs differ by more than one sound. The dictionary is now being searched for such pairs, and the results are included in the "cons" column in the vowel tables and the "vowel" column in the consonant tables.
• Related to the previous question is the problem of syllabic versus non-syllabic consonants. Is the contrast beween name and same of the same type as the contrast between button and butts?
• Can we admit minimal pairs where a sound is paired with a null? For example, could back and bank be a minimal pair? If so, the inventory of pairs would become much larger. I have begun to list these pairs, and they are shown in the "null" columns in the tables.
• In some cases the inflected forms of a base pair such as seep and scene appear to be non-minimal. Where the pronunciation /sip/ and /sin/ have only one difference, the -s ending turns them into /sips/ and /sinz/, apparently showing two differences. Some research carried out by Merwyn Torikian under my supervision in 1992 used sound analysis software to investigate this and found that the physical difference in the inflections is insignificant. In the case of pairs like docks/dogs or seeps/scenes, the whole syllable is affected by the voicing or devoicing, but the final /s/ or /z/ shows up on a spectrogram as almost identical. Therefore all such pairs (including past tense endings) have been added to the lists. This does lead to an anomaly in the case of the /t/ versus /n/ contrast, since a word like wits enters pairs with wins and wince.

You will find two related lists derived from the same dictionary source at the following links:

• RP homophones
• Homographs

Why did I start?

My personal interest in this topic may be due partly to the fact that I once lived in a flat in the village of Etiler near Istanbul. From the living room one had a view across a green meadow down towards the steep sides of the Bosphorus, where one constantly saw passing freighters, small cruise liners and even submarines. It was one of the few places in the world where one might have said "Look, there's a sheep!" and expect to be misunderstood. Nor do I want to disappoint all those who ask me about my grandfather, Professor Henry Higgins.

Reference

Keywords:

Selected as the Speech-Language Pathology Site of the Month, March 2007.