Since the phonetic representations of the diphthongs in words like "house" and "why" are /aʊ/ and /aɪ/ respectively, I would like to know the name of the first vowel that composes these sounds. In other words, what's the name of the vowel that starts both diphthongs? Is it the short o as in "hot" or the short a as in "apple"? I ask because I often hear a nasal sound when native English speakers (especially from the US) pronounce words like "out" or "house," and this makes me think that the starting vowel might be /æ/ as in "anthem" rather than /a/ as in hot — I guess /a/ is a short o. Is my observation correct and Americans pronounce the diphthong /aʊ/ starting with /æ/? Could you please clarify what is the name of this /a/ sound in English? Is it simply an "a" in general? How do you pronounce the /a/ at the beginning of both /aʊ/ and /aɪ/? Does it sound like a short o /ɒ/ as in "hot" or like a Spanish a \ä\ as in "car"?

Also, I stumbled across a website that explains the pronunciation of these diphthongs in a way that confuses me even more:

/aʊ/: "This diphthong is pronounced as a short A sound sliding into an "oo" sound."

Is the initial vowel really a short a, and does it slide into an "oo" long u /o͞o/ as in "food" or into a short u /ʊ/ as in book?

/aɪ/: "This diphthong is pronounced as a long I sound sliding into a long E sound."

Does it really start as a long I sound? Does it really slide into a long E sound or maybe into a short I sound as indicated by the symbol /ɪ/?

  • 1
    I don't have time right now to write an answer that addresses the things that you've confused in this post, but I do have a link to a chart showing where each diphthong starts and ends, so I thought I'd share that here, even though it's not really an answer: books.google.com/books?id=FjLc1XtqJUUC&pg=PA90
    – user230
    Commented Feb 18, 2016 at 9:37

1 Answer 1


The /a/ in the diphthongs, as its own phonemic sound, had originally vanished from many dialects of English all the way back in Middle English, centuries ago: in fact, it had disappeared around the 16th century and a modern short A took its place.

Here's /a/. https://en.wikipedia.org/wiki/Open_front_unrounded_vowel

But that short A is subject to variation. Australian English grew a central /a/ out of the short A in its flavour of trap-bath split. All Romance languages also have this central /a/ (what you call the "Spanish /ä/), so there's a start.

/a/ plus short I should eventually help you create the long I with enough work to get it into a diphthong.

/aʊ/ is /a/ + /ʊ/ in "book".

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