Vowels are letters of the alphabet that produce one single sound. There are five of them – [a], [e], [i], [o], [u]. Diphthongs typically produce two vowel sounds in one syllable. In other words, they’re the result of the pairing of two pure vowels. This is why they aren’t included on the IPA charts. It’s vital to note that the close blend of the two vowels makes vowel lose its pure quality.
There’s some debate about the number of diphthongs in American English. While some say it’s eight, others believe it’s ten.
According to some reliable sources, the eight primary diphthongs in English are:
- /eɪ/ as in pay, day, say
- /ɔɪ/ as in toy, boy, coy
- /aɪ/ as in buy, sky, tie
- /ɪə/ as in hear, pier, beer
- /eə/ as in pair, bear, and hair
- /əʊ/ as in no, oh, so
- /ʊə/ as in poor and tour
- /aʊ/ as in now, how, cow
The slash marks noticeable at the front are dictionary symbols that lexicographers use. They act as pronunciation guides. However, a much easier way to understand the diphthongs’ basic pronunciations is to observe the example words in each of the eight categories.
When teaching diphthongs to young learners, teachers should use adequate examples to make the concept easy to grasp. They may even weave diphthongs in short stories like these:
Jack put the money down on the table (eɪ). The next day, he used some of it to buy a tie (aɪ). Then, he went to the pier (ɪə) and drank lots of beer.
The origin of the word ‘diphthong’ can be traced to the Greek term diphthongos, which refers to “two tones” or “two sounds. Diphthongs are also called “gliding vowels” as one sound almost glides into the other. When the speaker pronounces the diphthongs, he can hear two vowel sounds, even though no syllabic break occurs.
Vowels are speech sounds. In some words, the vowel sound can be incredibly prominent and either long (like eagle, peach, or unicorn) or short (cat, can, end, or moss). In others, it can be silent, like in ‘aisle’ and ‘bread,’ the vowel ‘a’ is silent.
A speaker produces a vowel sound freely, without any friction. In other words, when making vowel sounds, the speaker doesn’t need to control his vocal tracts. However, a vowel doesn’t contain any gliding movement, unlike diphthongs.
Two components make up a diphthong – nucleus and off-glide. A nucleus refers to the central sound, which is emphasized more than the other vowel sounds. In contrast, the off-glide isn’t much stressed. Instead, it simply flows.
Studying diphthongs is a favorite activity among many linguists, primarily because they differ between languages, dialects, and continents. For instance, a diphthong that the New Yorkers have adopted includes an “aw” sound. Thus, when they pronounce “dog,” it sounds like “dawg.” Similarly, people in Birmingham, England, have adopted a diphthong that has an “oi” sound. Thus, if one can hear certain people in Birmingham pronouncing “nice,” it’ll sound more like “noice.”