Diphthongs are special vowel sounds where your mouth glides from one position to another within the same syllable. English has 8 diphthongs, and mastering them is essential for natural-sounding pronunciation.
What Are Diphthongs?
A diphthong (pronounced "DIF-thong") is a vowel sound that combines two vowel qualities in one syllable. Your mouth starts in one position and smoothly glides to another.
Simple vowel (monophthong): /iː/ as in "see" - mouth stays still Diphthong: /aɪ/ as in "my" - mouth moves from /a/ to /ɪ/
Think of diphthongs as "gliding vowels" - they move!
The 8 English Diphthongs
English has 8 diphthongs, which can be grouped into 3 categories:
Closing Diphthongs (mouth closes)
- /eɪ/ - as in "day"
- /aɪ/ - as in "my"
- /ɔɪ/ - as in "boy"
- /aʊ/ - as in "now"
- /oʊ/ - as in "go"
Centering Diphthongs (tongue moves to center)
- /ɪr/ - as in "here" (American English)
- /ɛr/ - as in "there" (American English)
- /ʊr/ - as in "tour" (American English)
Let's explore each one in detail!
1. The /eɪ/ Sound (as in "day")
This diphthong glides from /e/ to /ɪ/. Your mouth starts open and closes slightly.
Common Spellings:
- a-e: make, cake, game
- ay: day, say, play
- ai: rain, wait, train
- ey: they, grey, obey
- ea: great, break, steak
Practice Words:
2. The /aɪ/ Sound (as in "my")
This diphthong glides from /a/ to /ɪ/. Start with your mouth wide open, then close to a small smile.
Common Spellings:
- i-e: time, like, ride
- y: my, by, fly, sky
- igh: high, night, light
- ie: tie, pie, lie
- i: find, mind, blind
Practice Words:
3. The /ɔɪ/ Sound (as in "boy")
This diphthong glides from /ɔ/ to /ɪ/. Start with rounded lips, then spread into a smile.
Common Spellings:
- oi: oil, coin, point
- oy: boy, toy, enjoy
Practice Words:
4. The /aʊ/ Sound (as in "now")
This diphthong glides from /a/ to /ʊ/. Start with mouth open, then round your lips.
Common Spellings:
- ow: now, how, cow, down
- ou: out, house, about, loud
Practice Words:
5. The /oʊ/ Sound (as in "go")
This diphthong glides from /o/ to /ʊ/. Start with rounded lips and round them even more.
Common Spellings:
- o-e: home, phone, bone
- ow: show, know, slow
- oa: boat, coat, road
- o: go, no, so
Practice Words:
6. The /ɪr/ Sound (as in "here")
This centering diphthong glides from /ɪ/ toward /r/. (In British English, it glides toward schwa /ə/.)
Common Spellings:
- ear: hear, near, clear
- eer: beer, deer, steer
- ere: here, severe
- ier: tier, pier
Practice Words:
7. The /ɛr/ Sound (as in "there")
This centering diphthong glides from /ɛ/ toward /r/.
Common Spellings:
- air: air, fair, hair
- are: care, share, rare
- ear: bear, wear, pear
- ere: there, where
Practice Words:
8. The /ʊr/ Sound (as in "tour")
This centering diphthong glides from /ʊ/ toward /r/.
Common Spellings:
- oor: poor, moor
- our: tour, your, four
- ure: sure, pure, cure
Practice Words:
Minimal Pairs: Diphthong vs. Diphthong
Practice hearing the differences:
Common Mistakes
Mistake 1: Not Gliding
Wrong: Saying /e/ instead of /eɪ/ for "day" Fix: Make sure your mouth moves during the vowel
Mistake 2: Making Two Syllables
Wrong: "boy" as "bo-ee" (two syllables) Fix: Glide smoothly in one syllable
Mistake 3: Spanish Interference
Spanish speakers may substitute Spanish vowels:
- "my" as /mai/ (Spanish vowels) instead of /maɪ/ Fix: Practice the English target sounds
Mistake 4: Forgetting to Round Lips
For /aʊ/ and /oʊ/, your lips must round at the end. Fix: Exaggerate the lip rounding at first
Practice Sentences
/eɪ/ Practice:
"They say it may rain today." (ðeɪ seɪ ɪt meɪ reɪn təˈdeɪ)
/aɪ/ Practice:
"I like to fly my kite at night." (aɪ laɪk tə flaɪ maɪ kaɪt æt naɪt)
/ɔɪ/ Practice:
"The boy enjoys his toy." (ðə bɔɪ ɪnˈdʒɔɪz hɪz tɔɪ)
/aʊ/ Practice:
"How did you find out about the house?" (haʊ dɪd ju faɪnd aʊt əˈbaʊt ðə haʊs)
/oʊ/ Practice:
"Go show Joe the boat on the road." (ɡoʊ ʃoʊ dʒoʊ ðə boʊt ɑn ðə roʊd)
Tongue Twisters
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"May Day is a great day to play and stay away." (/eɪ/ practice)
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"My nice wife likes white rice at night." (/aɪ/ practice)
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"The noisy boy enjoys toys with joy." (/ɔɪ/ practice)
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"How now brown cow, out on the ground in town." (/aʊ/ practice)
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"Joe knows no snow will show on the road to home." (/oʊ/ practice)
Quick Reference Chart
| Diphthong | Example Words | Spelling Patterns |
|---|---|---|
| /eɪ/ | day, make, rain | a-e, ay, ai, ey |
| /aɪ/ | my, time, night | y, i-e, igh, ie |
| /ɔɪ/ | boy, oil, voice | oy, oi |
| /aʊ/ | now, out, house | ow, ou |
| /oʊ/ | go, home, boat | o, o-e, ow, oa |
| /ɪr/ | here, near, clear | ear, eer, ere |
| /ɛr/ | there, air, care | ere, air, are |
| /ʊr/ | tour, poor, sure | our, oor, ure |
Why Diphthongs Matter
Diphthongs are everywhere in English! Words like "I," "my," "you," "they," "day," "time," "now," and "go" all contain diphthongs. Mispronouncing them can:
- Cause misunderstandings: "boy" vs. "buy" mean different things
- Make you sound foreign: Pure vowels instead of glides mark non-native speech
- Affect your rhythm: Diphthongs affect syllable timing
Master these 8 sounds, and your English will sound much more natural!
Sources
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Phonetics References
- Ladefoged, P., & Johnson, K. (2014). A Course in Phonetics. Cengage Learning.
- Roach, P. (2009). English Phonetics and Phonology: A Practical Course. Cambridge University Press.
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Pronunciation Teaching
- Celce-Murcia, M., Brinton, D., & Goodwin, J. (2010). Teaching Pronunciation: A Course Book and Reference Guide. Cambridge University Press.