shwa vs murmur vowel

shwa and murmur vowel both are nouns.

Word	Noun	Adjective	Verb	Adverb
shwa	Yes	No	No	No
murmur vowel	Yes	No	No	No

As nouns, murmur vowel is a hyponym of shwa; that is, murmur vowel is a word with a more specific, narrower meaning than shwa:

shwa: a neutral middle vowel; occurs in unstressed syllables
murmur vowel: a schwa that is incidental to the pronunciation of a consonant

Other hyponyms of shwa include murmur.

shwa (noun)	murmur vowel (noun)
a neutral middle vowel; occurs in unstressed syllables	a schwa that is incidental to the pronunciation of a consonant