Someone has asked me to describe the difference in the vowel sounds of the words look and luke. So that would be, the 'uh' as in 'pull' [ʊ] and the 'oo' as in 'boo' [u] vowel sounds. The main difference is in the mouth position, what the lips do.
On look, uh, you can see, the corners come in, and, therefore, the lips come away from the face. On luke, lu-, they do the same, only the circle is tighter. That brings the sound more forward here in the mouth and also it brings the tongue forward just a little bit more. Let's look at some pictures. Here you see the two side-by-side. Clearly in the word pull, the lips form a larger circle than in the word boo. This means that the corners of the lips come in a little bit more. Again, in profile it is easy to see that the lips are further apart in pull, therefore making a larger circle. Notice in the word pull that the top lip is more angular as it pulls away from the face, whereas in the word boo, it is a little more rounded. The bottom lip also makes a sharper angle with the face in the word pull than it does on the word boo, as the lips stretch a bit more to make this bigger circle with the lips. Take a moment to study them in profile.
Watch the mouth as I read some words with the 'oo' as in 'boo' vowel: poodle, zoo, boom, boost, proof, shoot, choose, spoon.
And now as I read some words with the 'uh' as in 'pull' vowel: could, would, foot, full, book, crook. A few word pairs now.
The first word in each pair has the 'oo' as in 'boo' vowel sound, and the second the 'uh' as in 'pull'. Fool, full. Hoot, hood. Kook, cook. Nuke, nook.
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