The English language is a complex system, much like mathematics. Certain words fit together while others do not, and when paired correctly, sentences are formed. To some, the English language might seem a bit confusing and overwhelming because there are so many rules that must be followed. Even people who have always spoken English follow certain language rules every day without even realizing it.
One of these rules that English speakers effortlessly follow involves a natural sound change that occurs in many words that are used daily. A diphthong is the double vowel sound that can occur when there are two vowels side-by-side, such as in ''foil'' and ''pout,'' or in words with a single vowel, such as ''late'' and ''joy.''
Although a diphthong has two distinct vowel sounds, they remain within the same syllable, or unit of sound.
For example, ''join'' may sound as though it has two syllables, broken up like this: jo-in
However:
- The double vowel sound created by the letters ''oi'' is in fact part of the same syllable, so ''join'' is a single-syllable word.
The natural process of moving from one vowel to another when we pronounce diphthongs is called gliding. Say the word ''join'' out loud, and notice how easily your mouth moves from the ''o'' sound to the ''i'' sound in the word! It just glides right out, doesn't it?
The best way to determine if a word has a diphthong, with two vowel sounds, or a monophthong, with only one vowel sound, is to listen to how it sounds when you say it out loud. If the vowel sound changes within the same syllable, it's most definitely a diphthong.
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