Unstressed Vowels
* What they are: In spoken language, vowels in words can be pronounced with varying degrees of emphasis. An unstressed vowel is one that receives less emphasis than a stressed vowel.
* How they sound: Unstressed vowels often have a reduced sound, sometimes approaching a schwa sound (ə). This is the sound you hear in the "a" of "about" or the "e" of "the."
The Unstressed Vowel in "Sentence"
The word "sentence" has two vowels: "e" and "e."
* The first "e" is stressed and pronounced clearly.
* The second "e" is unstressed. In most pronunciations, it will have a reduced sound close to the schwa (ə).
In Conclusion:
The unstressed vowel in "sentence" is the second "e." It's the one that gets a reduced, less emphasized pronunciation.