Diphthong

he word diphthong comes from the Latin diphthongus, a word that at the same time has its origin in a word derived from Greek language. The term refers to the union or the combination of a pair of adjacent vowels that are expressed in the same syllable.  It is a vowel that has two different targets.

Related topics

Hiatus, triphthong

What is diphthong?

The diphthong is a type of sound chain that is formed by the articulation of two adjacent vowels followed by each other without any interruption, generating a smooth transition that characterizes the timbres of each vowels.

Definition

The diphthong is the union that occurs between two different vowels that are placed continuously within the same syllable and may be formed by an open vowel such as e, e, o, and a closed vowel such as i and u. The process by which one vowel sound moved to another is known as gliding, this is the reason why a diphthong is also called “gliding vowel”.  Another types of names to refer to this type of sound are compound vowels, complex or moving vowels.  It is important to mention that the sound change that converts a single vowel into a diphthong is known as diphthongization.

Diphthongs in English language

In English language, a diphthong is a one-syllable sound formed of two vowels.  In English pronunciation there are eight different diphthong sounds.  For example:

The sound /ei/ in play has two vowel sounds, /e/ and /i/.

Maybe the most important aspect when we refer to diphthongs in English is that they are not formed by two simple vowels together, but one long vowel where the pronunciation changes since the beginning to the end, in other words, the pronunciation changes completely at the end of the word.  The most common diphthongs in English, specially USA, are said to be /ow/, /ou/, /oy/ and /oi/ as in bow, ground, toy and coin.

Characteristics of English diphthongs

Their main characteristics are the following:

• Both vowels have to be lax.
• The first one is the most important in terms of stress. This means that, for example, in diphthong [aɪ], sound [a] is much longer and stronger than sound [ɪ].
• Vowels pronunciation take place through a glide, that is, through a continuous and very smooth movement from the first vowel to the second, in other words, they are not articulated distinctly. 

Types

There are two different types of diphthong, and these can be:

• Closing: this type of diphthong is the one in which the last vowel is near-high.  As the two vowels need to be lax, there are only two different possibilities [ɪ] and [ʊ].
• Centering: these ones ends in a vowel [ə] (schwa).

It is important to mention that diphthongs [aɪ], [eɪ], [ɔɪ], and [aʊ] can be found in British and American English, and [əʊ] only in British.

Most common diphthongs found in American English

The most common types of diphthongs that you can find in American English are the following:

/eɪ/: It has a Long A sound

This type of diphthong is very similar to the long A sound.  The correct way to pronounce it is as a long A sound sliding into a long E sound.  It is important to understand that some dialects pronounce the long A sound as one single sound.  There is also the case where is pronounce as two vowel sounds.  Some people who has a southern accent, mainly from the south part of the United States will stretch out the diphthong more.  Some examples are:

• day
• may
• clay
• away
• lay
• play
• eight

/aɪ/: This type of diphthong is pronounced as a long I sound sliding into a long E sound.

The sound of this diphthong can vary from one dialect to another one.  In some places the long I sound is pronounced in the words as one single sound. Some dialects pronounce the vowel sound more like the “AH” sound you would here in “ball”.  Or it can also be pronounced as two vowel sounds.  Some examples of words with this type of diphthong are:

• sky
• try
• fry
• pie
• cry
• tie
• why
• eye

/ɔɪ/: This one is pronounced as a long O sound, in this case, the sound quickly slides into a long E sound.  Some examples of this type of diphthong are:

• joy
• annoy
• enjoy
• ploy
• soil
• boil

/ɪə/: It is pronounced as a long E sound sliding into an Ur sound.  The examples are:

• pier
• hear
• steer
• clear
• fear

/eə/: This diphthong is pronounced as a long A sound sliding into a U sound.  Examples:

• beard
• hair
• fair
• stairs
• pair
• wear
• where

/aʊ/: Is pronounced as a short A sound sliding into an “oo” sound.  Some examples of this type of diphthong are the following:

• brown
• cow
• how
• frown
• now
• wow

/oʊ/: This diphthong is frequently used and only pronounced as a single long O sound.  It is important to remember that this type has a long O sound sliding into an “oo” sound.  Some examples are:

• yellow
• coat
• float
• though
• toe
• no
• low
• although