What are Diphthongs?

What are diphthongs?

Diphthongs are the sounds formed by the combination of two vowels in a single syllable, in which the sound begins as one vowel and moves towards another, for example in the words boy or bye. American English is said to have 8 diphthongs.

Why should I know what a diphthong is?

An important thing to remember about diphthongs in English is that they are not simply two vowels or two vowel sounds that are spoken as two separate sounds. Instead, the sound is one long vowel sound where the pronunciation changes from the beginning to the end. For this reason, diphthongs are also referred to as gliding vowels: the sound glides from one sound to the next without an obvious gap between the sounds or the creation of a separate syllable. Knowing this will help you to pronounce the sounds like native speakers do.

How do I know which sounds are pronounced as diphthongs and which ones as monophthongs?

This is where phonetic notations can help you. If you simply memorize the 8 diphthong sounds in American English, you will always recognize these combinations whenever you’re looking up a word in a dictionary. You’ll notice below that we’ve included a few diphthongs unique to British English as well. 

  • /aɪ/ This diphthong creates sounds similar to “eye”. Letter combinations that include “i”, “igh”, and “y” can create this sound. Examples: price, high, why
  • /eɪ/ This diphthong creates sounds similar to “ate”. Letter combinations that include “ey”, “ay”, “ai” and “a” can create this sound. Examples: face, way, hey 
  • /ɪə/ This diphthong creates sounds similar to “ear”in British English. Letter combinations such as “ee”, “ie” and “ea” can create this sound. Examples: here, fear, pier in  British English 
  • /ɔɪ/ This diphthong creates sounds similar to “boy”. Letter combinations such as “oy” and “oi” can create this sound.  Examples: coin, noise, soy
  • /oʊ/ This diphthong creates sounds similar to “boat”. Letter combinations such as “ow”, “oa” and “o” can create this sound. Examples: know, moan, go
  • /aʊ/ This diphthong creates sounds similar to “ow!”. Letter combinations such as “ou” and “ow” can create this sound. Examples: “How now, brown cow?”
  • /eə/ This diphthong creates sounds similar to “air” in British English. Letter combinations such as “ai”, “a”, and “ea” can create this sound. Examples: mare, fair, pear in British English.
  • /ʊə/ This diphthong creates sounds similar to “sure” and most occurs with the letter “u”. Examples: lure, pure, furious in British English. 

We will focus on each of these vowel combinations in separate blog posts, exploring in depth how you can produce these sounds and where you can find these sounds.

Need help?

For more on diphthongs, check out these articles:

Do you need a little more help with your pronunciation?  To learn more about English pronunciation, get needed feedback and practice in conversation, join SpeakUp, a dynamic program that engages you in authentic conversations on relevant topics and provides you with feedback from a professional and experienced English teacher.  In fact, the first week is free for you to try it out!

Sabine Hobbel

Sabine Hobbel

Sabine Hobbel has been helping people improve their English since 2004; the knowledge she gained from completing her Master's degrees in Psychology and in English helps her every day. She has lived in 4 different English-speaking countries and she currently lives in the Italian Alps.
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