English monophthongs and diphtongs

Diphthongs and Gliding Vowels
A single vowel, such as the “O” or “I” in “oil” is called a monophthong (mono for one, di for two). An example of a monophthong is the “O” in “hop.” But, when we move from one vowel sound to another, such as the “oi” in “oil,” it’s called gliding. As such, diphthongs are sometimes referred to as “gliding vowels.”
Linguists love studying diphthongs because they vary between dialects, languages, and continents. For example, New Yorkers adopted a diphthong that features an “aw” sound. An example would be the way certain New Yorkers pronounce “dog” in a manner that sounds more like “dawg.”
Likewise, folks over in Birmingham, England adopted a diphthong that features an “oi” sound, among others. An example would be how certain folks in Birmingham pronounce “nice” in a manner that sounds more like “noice.”
8 American English Diphthongs
Considering the intricacy of the subject, you won’t be surprised to learn there are dividing opinions about the number of diphthongs in American English. Some will say eight; others ten.
You’ll notice that, in some of the examples below, there’s only one vowel. How can this be a diphthong, you say? Well, whenever there’s movement in your mouth as you pronounce the letter and it makes a long vowel sound, it’s mimicking two vowels. That’s why the “di” or “two” remains, even though there may be only one vowel written.
Perhaps the easiest way to recognize a diphthong is to listen to the sound created by the vowel or vowels when you say it out loud. If the vowel sound changes, you’ve got yourself a diphthong. Without getting too detailed (or any more confusing), let’s look at eight of the heavy-hitters.

The diphthongs are listed below with examples of words where they occur.
A diphthong is a vowel sound with a deliberate glide. It is represented in phonetic transcription by a sequence of two elements (Symbols). The first element shows the position of the organs of speech at the beginning of the glide. The glide terminates on the second element.

A diphthong consists of a single syllable. That is, the vowel glide must be performed within one syllable. You must remember that the length and stress are concentrated on the first element of a diphthong. The second element is made less prominent.

/aɪ/
This diphthong uses letters and letter combinations like /i/, /igh/, and /y/ to form sounds similar to “eye.” Here are a few more examples:

• 
  Cry
  
• 
  My
  
• 
  Like
  
• 
  Bright
  
• 
  Lime
  

/eɪ/
This diphthong uses letters and letter combinations like /ey/, /ay/, /ai/ and /a/ to form sounds similar to “great.” Here are a few more examples:

• 
  Bake
  
• 
  Rain
  
• 
  Lay
  
• 
  Eight
  
• 
  Break
  

/əʊ/
This diphthong uses letters and letter combinations like /ow/, /oa/ and /o/ to form sounds similar to “boat.” Here are a few more examples:

• 
  Go
  
• 
  Oh
  
• 
  Slow
  
• 
  Loan
  
• 
  Though
  

/aʊ/
This diphthong uses letters and letter combinations like /ou/ and /ow/ to form sounds similar to “ow!” Here are a few more examples:

• 
  Bound
  
• 
  House
  
• 
  Brown
  
• 
  How
  
• 
  Now
  

/eə/
This diphthong uses letters and letter combinations like /ai/, /a/, and /ea/ to form sounds similar to “air.” Here are a few more examples:

• 
  Pair
  
• 
  Lair
  
• 
  Stare
  
• 
  Care
  
• 
  Bear
  

/ɪə/
This diphthong uses letters and letter combinations like /ee/, /ie/ and /ea/ to form sounds similar to “ear.” Here are a few more examples:

• 
  Career
  
• 
  Here
  
• 
  Near
  
• 
  Year
  
• 
  Pier
  

/ɔɪ/
This diphthong uses letters and letter combinations like /oy/ and /oi/ to form sounds similar to “oil.” Here are a few more examples:

• 
  Boy
  
• 
  Coy
  
• 
  Toy
  
• 
  Foil
  
• 
  Coin
  

/ʊə/
This diphthong uses letters and letter combinations like /oo/, /ou/, /u/, and /ue/ to form sounds similar to “cure.” Here are a few more examples:

• 
  Fur
  
• 
  Sure
  
• 
  Lure
  
• 
  Pure
  
• 
  Manure
  

Description:

• 
  The glide begins from /ɪ/ and moves towards /ə/
  
• 
  The lips are neutral.
  

Spellings:
eer – deer / dɪə/
ear – dear / dɪə/, fear / fɪə/
ere – here / hɪə/
eir – weired / wɪəd/
ier – fierce / fɪəs/
ea – idea / aɪdɪə/