A diphthong is a glide from one vowel sound to another within a single syllable (e.g., the phoneme // in the words I, my  or try). This is different from a monophtong, where there is just one vowel sound (/æ/ in man or sand).

Unlike Spanish, in English diphthongs are normally considered just one phoneme, not the combination of two. Here are the eight English diphthongs:


Table 1


here, near, deer, weird



endure, tour, pure, poor

make, brain, play, eight, great, they


go, low, bode, boat, toe, so, shoulder


boy, toy, noise, voice

there, air, share, rare, pear, bear

time, type, my, lie, buy, eye, high, height,

how, loud, mouse, about, cow, allow,



Diphthongs are one of the greatest sources of mispronunciation for Spanish speakers. The main difficulty is that English letters can be pronounced in several ways, so sometimes it’s difficult to know which is the correct one. An  can be said as /ɪ/ or //, an o as /ɒ/ or /əʊ/, etc. We must also remember that vowels are often pronounced /ə/ when they are unstressed. This uncertainty leads to very common mistakes. Let’s see some examples of words which are often mispronounced by Spanish speakers.

                                  Right                                                                          Wrong

since                       sound_loud_speaker /sɪns/                                                                     sound_loud_speaker /sains/*

abroad                  sound_loud_speaker /əˈbrɔːd/                                                             sound_loud_speaker /aˈbroud/*

afraid                    sound_loud_speaker /əˈfrd/                                                              sound_loud_speaker /aˈfred/*

said                        sound_loud_speaker /sed/                                                                      sound_loud_speaker /sd/*

both                       sound_loud_speaker /bəʊθ/                                                                   sound_loud_speaker /boθ/*

old                           sound_loud_speaker /əʊld/                                                                    sound_loud_speaker /old/*

comfortable      sound_loud_speaker /ˈkʌmftəbl/                                                        sound_loud_speaker /komforˈteibol/*

Ian                          sound_loud_speaker /ˈən/                                                                    sound_loud_speaker /ˈaian/*

image                    sound_loud_speaker  /ˈɪmɪʤ/                                                               sound_loud_speaker /iˈmeiʤ/*

famous                 sound_loud_speaker /ˈfməs/                                                             sound_loud_speaker /ˈfamous/*


However, the glides included in Table 1 don’t exhaust the subject of diphthongs, not in the sense we, Spanish speakers, understand them in any case (there seem to be differences in the criteria we use to classify very similar phenomena).

There are English words such as music /ˈmjuːzɪk/, new /nju:/, one /wʌn/, win /wɪn/ or when  /wen/ that we would immediately think of as diphthongs. But if they are not diphthongs in English, what are they, then? These words include sounds which are called semiconsonants or even semivowels sometimes (/j/ and /w/, explained here and here), which are very similar to vowels but not exactly the same, and that’s why they are left out of the table. However, to have the whole picture in mind, it is advisable to be aware of their existence and to know how they are considered in English.


And here are a couple of examples of diphthongs pronounced by native speakers:

sound_loud_speaker Well, I thought I’d given loads away. I think I’m full of sort of heartfelt personal details about my joys and pains (David Mitchell, BBC4)

sound_loud_speaker There’re jokes about the aging process (John Wilson, BBC4).


There are no absolute rules that will always allow us to know if a vowel is pronounced as a monophthong or as a diphthong, but fortunately we can use a couple of very useful guidelines. Let’s see them.


1. Double consonants. When a vowel is followed by a double consonant, it is always pronounced as a monophthong (most of the times, a short one).

sound_loud_speaker apple          sound_loud_speaker bottle          sound_loud_speaker daddy           sound_loud_speaker buzz          sound_loud_speaker class            sound_loud_speaker dinner   (but sound_loud_speaker diner)

I only know one exception to this rule, the word bass (lowest tone in music), which is pronounced /bs/. When the word bass means a type of fish, it is pronounced /bæs/ instead.

2. The silent magic eHave a look at the following comparison.

sound_loud_speaker mad         sound_loud_speaker made                      sound_loud_speaker fat          sound_loud_speaker fate                        sound_loud_speaker hat            sound_loud_speaker hate

sound_loud_speaker met          sound_loud_speaker mete                      sound_loud_speaker pet          sound_loud_speaker Pete                      sound_loud_speaker gen            sound_loud_speaker gene

sound_loud_speaker sit              sound_loud_speaker site                          sound_loud_speaker fin          sound_loud_speaker fine                         sound_loud_speaker Tim          sound_loud_speaker time

sound_loud_speaker cloth        sound_loud_speaker clothe                    sound_loud_speaker cod        sound_loud_speaker code                       sound_loud_speaker not           sound_loud_speaker note

sound_loud_speaker cut             sound_loud_speaker cute                        sound_loud_speaker us            sound_loud_speaker use                        sound_loud_speaker cub           sound_loud_speaker cube


An old English saying goes “silent final e makes the vowel say its name”. As you can observe, the addition of a silent e  to many words not only changes its meaning but the pronunciation of the previous vowel as well. This stops being a short vowel and it’s pronounced with its alphabet name: a // (made); e /i:/ (gene); i // (time); o /əʊ/ (note); u, /ju:/ (cute). The new vowel is a diphthong in all the cases but the e, which is pronounced as a long /i:/.

The silent e, which is often called the magic e, cannot be taken as a rule, because there are plenty of exceptions (some of them as common as love or have), but it does give a clue as to the pronunciation of the vowel in a great number of cases.


Now, if you want to further refine your pronunciation of diphthongs, here are five interesting points to take into account.


Five points about diphthongs

1. Length. Diphthongs last more or less the same as a long vowel (/ɑː/, /ɔː/, etc.).

2. Unequal vowels. The first element is longer and more stressed (the /a/ part of the diphthong // in time, for instance). The second element can be considerably weakened.

3. Not like in Spanish. When you find the sounds /a/ or /ɔ/ as part of the diphthong, you can pronounce them as in Spanish because they sound very similar. You can do this with the /a/ in time or the /ɔ/ in joy, but the other vowels are quite different. So it is advisable to check how these sounds (/e/, /ɪ/, /ə/ and /ʊ/) are pronounced in the corresponding sections.

4. Watch these two! I recommend to be particularly careful with two diphthongs, /əʊ/ and //.

5. Pre-fortis clipping. Diphthongs are shortened by following voiceless consonants in the same way pure vowels are (this process is known as pre-fortis clipping). You can observe this difference in length in the recordings included in table 3. Boat is shorter than bode, make than brain and type than time. This is because /t/, /k/ and /p/ are voiceless whereas /d/, /n/ and /m/ are voiced.



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