murmur vs shwa

murmur and shwa both are nouns.

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

As nouns, shwa is a hypernym of murmur; that is, shwa is a word with a broader meaning than murmur:

Other hypernyms of murmur include schwa.

murmur (noun)	shwa (noun)
a complaint uttered in a low and indistinct tone	a neutral middle vowel; occurs in unstressed syllables
a schwa that is incidental to the pronunciation of a consonant
a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech
an abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves

murmur (verb)	shwa (verb)
speak softly or indistinctly
make complaining remarks or noises under one's breath