W as a “vowel”
Any linguist will tell you that the “vowels” of English are not A, E, I, O, U, Y, and W. Those are letters (vowel letters, perhaps). Vowels are sounds we make with the mouth and throat. W is no more a vowel than A is. Letters don’t make sounds, people do. (Go ahead, listen to a newspaper or book.) Letters are written symbols we use to represent the sounds of spoken language. Yes, common usage of the word “vowel” more often refers to a letter, and that usage has led to this denotation in the dictionary. Nevertheless, this has only muddled popular notions of English phonetics, and of language itself.
In fact, the example(s) of OW as in how, and OU as in house are both the same vowel. (Just say the worlds out loud, and you’ll notice it’s the same vowel sound.) The International Phonetic Alphabet (IPA) records this sound like this: /au/. The complete words in the examples: /hau/ and /haus/ respectively. The only difference between the two words is that the second word has a final consonant.
Yes, the sound in question is a dipthong, but in English (as opposed to, say, Spanish), dipthongs are so closely blended that they constitute a single, distinct vowel sound. The words how and house both have just one, single vowel.
English has at least 21 vowels–more, depending on how you define things such as “r-coloring”–compare the vowels (the sounds) in the words he and her. (Notice that her is not pronounced like here.)
So to say that a letter–or a combination of letters–“sounds” a particiular way, is just inadequate, and distorts one’s understanding of language. Take, for example, the letters OU. Notice how many different vowels they represent:
Each word has a single, distinct, and different vowel. To say “the OU sound” is inadequate–which OU sound? Just as it is to say “the A sound”–which? The one in hat or hate? And to say “long A” or “short A” is also inadequate, because what about father?
This problem is partly the result of using print to describe sounds (which is why they created the IPA, a system of symbols used to record unique language sounds in print). But it’s also a result of people thinking that writing drives speech. Speech is a natural, human trait, while writing is artificial. To be certain, writing has evolved qualities which can’t be attained in speech (e.g., paragraphs, punctuation, etc.). And written languages have been created which have no spoken basis (mathematics, computer programing). But when it comes to vowels and consonants, speech drives the writing, not the other way around.