Diphthongs are sounds which consist of a movement from one vowel sound to another. Basically there are two vowel sounds pronounced together. Diphthongs are of a great importance because they are responsible for the “foreign” accent.
Usually, learners of English produce a pure vowel where a diphthong is required. Using a vowel instead of a diphthong is a common mistake for Vietnamese learners of English. As an example, the word “cake” is pronounced /kek/ instead of /keɪk/.
There are eight diphthong is English language. I classified them into three categories, in order to remember them easier, according to their ending.
Diphthongs that end in ə
ɪə (as in the word “dear”)
eə (as in the word “hair”)
ʊə (as in the word “newer”)
Diphthongs that end in ɪ
eɪ (as in the word “day”)
aɪ (as in the word “guy”)
ɔɪ (as is the word “noise”)
Diphthongs that end in ʊ
əʊ (as in the word “home”)
aʊ (as in the word “mouse”)
The diphthong ɪə
The starting point of this diphthong is closer than the sound /ɪ/ in the words “bin” or “bit”
Examples: dear, beard, beer, fierce
The diphthong eə
This diphthong starts with the /e/ sound (the sound from the words “get”, “men” etc) and ends with a schwa sound.
Examples: scare, hair, pear, bear
The diphthong ʊə
This diphthong has the starting point very close to the sound /ʊ/ from the words “put” or “pull”.
Examples: tour, newer, moored
These first three diphthongs end with a glide towards a closer vowel so they are called closing diphthongs.
The diphthong eɪ
This diphthong has as starting point the vowel /e/ as in the word “get” or the word “men”.
Examples: day, paid, face
The diphthong aɪ
The starting point of this diphthong is very similar to the sound /ʌ/ (as in the word “cut”) which is an open vowel between front and back.
Examples: guy, nice, time
The diphthong ɔɪ
The first part of this diphthong has the same sound as /ɔ/ in the word “born”.
Examples: noise, soy, coin, boil
The following two diphthongs glide towards /ʊ/ sound (as in the word “book”) which requires a rounding movement of the lips. However, since the second part of the diphthong is weak, the rounding movement of the lips is not very large.
The diphthong əʊ
This diphthong has a beginning sound very similar to schwa sound (as in the word “about”). The lips are slightly rounded just because of the ending sound /ʊ/ of this diphthong.
Examples: home, load, most
The diphthong aʊ
This diphthong begins with a vowel similar to /ɑ/ (as in the word “car”).
Examples: mouse, house, loud, pound