Included below are past participle and present participle forms for the verb murmur which may be used as adjectives within certain contexts. Low, indistinct (of a sound); reminiscent of a murmur.

Can sounds be an adjective?

sound (adjective) sound (adverb) sound (noun) ... sound wave (noun)

What type of noun is murmur?

1[countable] a quietly spoken word or words She answered in a faint murmur.