Semi-vowel W and Y

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What makes a sound a semi-vowel?

The /w/ sound (letter "w") and /j/ sound (letter "y") are the only two semi-vowels (also commonly called glides) in English. These sounds can be created with slightly greater restriction in the vocal tract than vowels, but less restriction than most other consonants.

The /w/ sound and /j/ sound are known as "semi-vowels" for many good reasons. Because the letters "w" and "y" can be used to spell vowel sounds and because the /w/ sound and /j/ sound are each a portion of two-sound vowels, they are sometimes thought of as vowel sounds. However, the /w/ sound and /j/ sound are not vowel sounds because they cannot be syllabic (they cannot create a syllable). For example, if the /w/ sound and /j/ sound could create a syllable, the words when, we, you, and year (among many others) would be pronounced with two syllables.

Additional confusion is created because both the /w/ sound and /j/ sound can combine with vowels to create two-sound vowels. These cases are separate from the use of "w" and "y" as representatives of distinct vowel sounds, however.

Vowel Sounds spelled with "w" and "y"

Generally speaking, the letters "w" and "y" will represent a /w/ sound or /j/ sound when they are:

(a) at the beginning of a word (will, you)
(b) the first letter of part of a compound word (homework, backyard)
(c) the first letter after a prefix (rewind, beyond)

Additionally, the letter "w" usually represents a consonant sound when it follows another consonant, such as in the word sweet.

In other positions within a word, the letters "w" and "y" are usually associated with the spelling of a vowel sound. When the letters "w" and "y" are used in vowel spellings, they are representing the vowel sound, and not a /w/ sound or /j/ sound.

Vowel sounds spelled with a "w":

aw /ɑ/ saw
ew /u:/ new
ew /ju:/ few
ow /oʊ/ snow
ow /aʊ/ cow

Vowel sounds spelled with a "y":


y /i/ happy
y /aɪ/ by
y /ɪ/ mystic
oy /oɪ/ toy
ay /eɪ/ day

Review of two-sound vowels

A two-sound vowel is a vowel sound that includes a /w/ sound or a /y/ sound in the pronunciation. Often, the /w/ sound or /y/ sound is only a minor part of the sound, but must be included for the sound to be pronounced fully. Two-sound vowels are known linguistically as diphthongs.

In long vowels:
a=/eɪ/, i=/aɪ/, o=/oʊ/, u=/ju:/, ow=/aʊ/ sound, and oy=/oɪ/ sound are two-sound vowels.

Linking vowels with semi-vowels

A slight /w/ sound or /j/ sound may be added into or between words when there would otherwise be two adjacent vowel sounds. The addition of the semi-vowel sound helps the speaker clearly articulate both vowel sounds. If the first vowel is a two-sound vowel that already ends in a slight /w/ sound or /j/ sound, the semi-vowel will be made more significant. Although native speakers regularly and naturally add these sounds to their speech, dictionaries do not include the added sound in their transcriptions.

Adding a /w/ sound Between Vowels:

heroic /hɪˈrowɪk/ (/oʊ/+/ɪ/)
fluent /ˈflu:wənt/ (/u:/+/ə/)

Adding a /j/ sound Between Vowels:

idea /aɪˈdi:jə/ (/i:/+/ə/)
science /ˈsajəns/ (/aɪ/+/ə/)

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