Tricky Vowel Sounds (Monophthongs, Diphthongs, and Triphthongs)  

Vowel sounds are an especially tricky part of English pronunciation because of how flexible and malleable they can be. While consonant sounds are fairly uniform throughout various dialects, vowel sounds can have slight variations in pronunciation from one region to another.

Another aspect of vowel sounds that can be confusing is when multiple vowel sounds blend together within a single syllable. Because there are no clear divisions between the sounds like there are for consonants, these blended vowel sounds can be difficult to pronounce correctly. In this section, we’ll look at the three ranges of vowel sounds: monophthongs (single vowel sounds within a syllable), diphthongs (two vowels sounds combined within a syllable), and triphthongs (three vowels sounds combined within a syllable).

The most basic vowel sound is known as a monophthong (pronounced /ˈmɑnəfˌθɑŋ/). As the prefix “mono-” suggests, a monophthong is a single sound (to which the root “-phthong” refers) within a single syllable. Most of these are short vowels, though there are some long vowel monophthongs as well.

Most of the monophthongs in English are commonly known as “short vowels,” which are usually produced when a vowel is followed by one or more consonants in a syllable.

Most vowel letters have a specific short-vowel sound, though U can create two types of short-vowel sounds. The semi-vowel Y can also create a short vowel sound, but it is the same as the letter I.

Let’s look at some examples of each type of short vowel:

Most of the traditional “long vowels” (vowel sounds that approximate the name of their corresponding vowel letters) are diphthongs, so we’ll look at those further on. One traditional long vowel that is a monophthong, though, is “long E,” represented in IPA by /i/. This sound is usually produced by the letter E, but it can also be formed by the letter Y, as well as a number of vowel digraphs. For example:

There are also a few other long vowels besides those that sound like the names of vowel letters. Most of these occur in various vowel digraphs, though some can be produced by single letters, while others occur when a vowel is combined with the consonant R.

A diphthong (pronounced /ˈdɪfθɔŋ/) is a single-syllable vowel sound in which the beginning of the sound glides to another, slightly different vowel sound. For this reason, diphthongs are often referred to as gliding vowels.

There are eight vowel sounds in American English that are generally agreed upon as being diphthongs. Four of these are the “traditional” long vowels (vowel sounds that are pronounced the same way as the names of the letters), but there are also a few others that occur with certain vowel digraphs or in combination with the letter R.

We’ll briefly go over the different diphthongs here, but you can continue on to the full section on Diphthongs to learn more.

With the exception of long E (/i/), all of the traditional long vowel sounds are diphthongs. These most predictably occur when the vowel letter is followed by a single consonant and a silent “e”:

This diphthong is pronounced “au-ee,” and it occurs in in the vowel digraphs OY and OI. For example:

This diphthong is pronounced “ah-oo,” and it occurs with the digraphs OU and OW. For example:

Depending on dialect, the schwa (/ə/) that forms the second part of this diphthong is often not pronounced. When this diphthong is articulated fully, it is pronounced “ih-uh,” and it usually occurs with the digraphs EE, EA, and IE when they are followed by an R. For example:

Like /ɪə/, the schwa of /ɛə/ is often left out. When it is articulated fully, /ɛə/ is pronounced “eh-uh,” and it usually occurs with the letter combinations ARE, AIR, and occasionally EAR. For example:

Very rarely, a single syllable may contain three vowel sounds that quickly glide together; this compound vowel sound is known as a triphthong (pronounced /ˈtrɪf θɔŋ/).

There are three triphthongs that are generally agreed upon in American English: /aʊə/ (“ah-oo-uh”), /aɪə/ (“ah-ih-uh”), and /jʊə/ (“ee-oo-uh”). We’ll briefly look at each here, but you can find out more about them in the full section on Triphthongs.

This triphthong is pronounced “ah-oo-uh,” and it occurs when the digraph OU is followed by an R. For example:

This triphthong is pronounced “ah-ih-uh,” and it occurs with the letter combination IRE. For example:

This triphthong is pronounced “ee-oo-uh,” and it sometimes occurs when the combination UR comes after a hard consonant and is followed by an E, Y, or I. For example: