What is the schwa vowel sound in gravel?

The schwa sound in "gravel" is the ə sound, represented by the vowel in the second syllable, "avel".

Here's how to think about it:

* Schwa is a very short, unstressed vowel sound. It's the most common vowel sound in English.

* In "gravel", the stress is on the first syllable "grav". This makes the vowel sound in the second syllable, "a", very short and unstressed.

* This unstressed "a" sound is pronounced as the schwa sound (ə).

So, the word "gravel" is pronounced as ˈɡræv.əl.