Meanings of open vowel in English

The melodies of Poe's prose linger, too, with his consummate control of cadence and of open vowel sounds.

To this inhuman and appalling song were set loud open vowels rather than words.

Melodies should go up on open vowels in the lyrics-A, I or O. E is half open and U is closed.

"Sorry I'm late," she said, her open vowels oozing down the aisle towards the stage.

And the Latin language is so particular on this point, that no one can be so ignorant as to leave quantities of open vowels.

He took immense pains to avoid the clash of "s" with "s," and to secure the predominance of open vowels when rhythm rendered them appropriate.