Diphthongs: The Sliding Vowels

A diphthong occurs when there are two separate vowel sounds within the same syllable. Indeed, the word, diphthong comes from the Greek word diphthongos, which means "two sounds" or "two tones." It is also known as a "gliding vowel," because the one sound literally glides into another. The words "boy," "because," "raw," and even "out" are examples of words that contain diphthongs. Diphthongs can be composed of one or two vowels.

Read on to learn a bit more about what diphthongs are, why they're important in the English language, and even how to recognize them.

The Primary Diphthongs

There are eight primary diphthongs in the English language, according to TutorEd and Stack Exchange. They are:

• /eɪ/ as in day, pay, say, lay
• /aɪ/ as in sky, buy, cry, tie
• /ɔɪ/ as in boy, toy, coy or the first syllable of soya
• /ɪə/ as in beer, pier, hear
• /eə/ as in bear, pair, and hair
• /ʊə/ as in tour, poor or the first syllable of tourist
• /əʊ/ as in oh, no, so, or phone
• /aʊ/ as in all the words of "How now brown cow!"

The opening letters (between the slash marks at the front) are dictionary symbols used by lexicographers. They are meant to serve as pronunciation guides, but you really only need to know them if you are looking up one of the words in a dictionary and wonder what these strange markings mean. The sound symbols can give you a simple way to distinguish between the eight diphthongs. A much simpler way to understand the basic pronunciations of the diphthongs, though, is to look at the example words in each of the eight diphthongs.

Diphthongs in Sentences

If you're teaching students about diphthongs, it might be helpful to provide sentences to illustrate. Doing so in the order the diphthongs are listed in the previous section in a short, funny story can make the concept clearer for young learners. So, you might have: 

After I get paid, today, I say I'll lay the money down on the table (eɪ). After I looked up in the sky, I did cry after I bought a tie (aɪ). The boy with the toy proved to be rather coy (ɔɪ). I hear that they drink lots of beer at the pier (ɪə). 

The pair of bears I encountered in the woods made my hair stand on end (eə). The tour provided a glimpse of the poor conditions in the country—but what did I know: I was just a tourist. (ʊə). Oh, no!! It's so boring to talk on the phone (əʊ). Wow, now there's a very brown cow (aʊ). 

You might also give students a list of words with diphthongs and have them make up their own sentences. 

Diphthongs vs. Triphthongs

There are blended sounds in English where vowels make three distinct sounds in a single syllable, called triphthongs. Some examples provided by English EFL include:

/eɪə/ as in layer, player
/aɪə/ as in lire, fire
/ɔɪə/ as in loyal, royal
/əuə/ as in lower, mower
/auə/ as in power, hour

That extra, or third, symbol that indicates that these are triphthongs, "ə," is a phoneme called a schwa and is roughly pronounced "uh." For some added pronunciation practice, give your students a few sentences containing triphthongs, such as:

The player had a great game for his team (eɪə), but when he got home his house was on fire (aɪə). Since he had been loyal to the royal court (ɔɪə), the king gave him a lower price for the new mower (əuə). Within an hour, he had the machine working at full power.

Of course, you don't have to use sentences that rhyme, but often expressing new concepts in songs, rhymes and funny sentences can focus students' attention and help them learn the concept.