Some time ago, I encountered the sentence:
Who would know aught of art, must learn, act, and then take his ease
as an example of the vowel sounds of English.
A few days ago, for no apparent reason, I got thinking about this again, specifically “Hang on, there aren’t enough words/vowels in there”. It has 14 words and vowels. Most varieties of English have more (though the number and exact line-up varies). My generally standard Australian English has 20, which matches the Macquarie Dictionary’s count. Further, the six which are missing are all diphthongs, but know and take are there. I searched online and found a blogpost by Lauren Gawne (a fellow Australian) from last year. She quotes a post by John Wells (an Englishman), who says he doesn’t know its origin, then (among other things):
[It] is sentence that not merely contains 14 [different] vowel sounds, but has the sound in a particular order (going clockwise more or less round the periphery of the vowel area) … to work properly the sentence requires the speaker to use RP [received pronunciation, standard British English] or something similar, with strong forms of would, of, and must, which in ordinary speech are usually weakened, but a weak form of and … the sentence covers only the monophthongs and narrow diphthongs. To complete it with the remaining diphthongs aɪ aʊ ɔɪ ɪə eə ʊə we would need something like “My loud voice nears their moors”. Or has someone got something better?
I had not previously encountered the term narrow diphthongs, but Wikipedia defines them as “are the ones that end with a vowel which on a vowel chart is quite close to the one that begins the diphthong”, for example, the /oʊ/ of know and the /eɪ/ of take. Wide diphthongs, then, “require a greater tongue movement, and their offsets are farther away from their starting points on the vowel chart”.
His second sentence doesn’t work for me, for two reasons. Firstly, for me, moor is /mɔ/. Macquarie gives only /mɔ/ but Oxford Living Dictionaries gives /mɔ/ and /mʊə/. Wells, being English, presumably uses /mʊə/. (Those two dictionaries treat poor the same way.) Secondly, the whole sentence just doesn’t make enough sense. How about: “My loud voice cheers their tours”. (Just to confuse the issue, Macquarie gives /tʊə/, /tuə/ and /tɔ/, while Oxford gives only /tʊə/.)