* The "pure" vowel concept is a little fuzzy: In phonetics, vowels are sounds produced without any obstruction of airflow in the mouth. However, English vowels often have some degree of constriction, making them not entirely "pure."
* Diphthongs complicate things: Diphthongs are vowel sounds that glide from one position to another within a single syllable (like the "ou" in "house" or the "oi" in "boy"). Do we count them as "pure" vowels?
So, depending on how strictly you define "pure vowel," the answer could be:
* 5: If you only consider the "purest" vowels with no movement or glide (like the "a" in "father," "e" in "bed," "i" in "machine," "o" in "go," and "u" in "flute").
* 12: If you include diphthongs and consider the various pronunciations of vowels in different words (like the "a" in "cat" vs. the "a" in "father").
Ultimately, it's more helpful to think of English vowels as having a spectrum of purity, rather than a rigid classification.