dull, faint, low, quiet, soft | general
a general murmur of assent

angry

give, let out
He gave a little murmur of relief.

hear

rise, run
A murmur of excitement rose from the audience. | A murmur of amusement ran round the room.

in a ~
She answered in a low murmur.

with a ~
He took the mug of coffee with a murmur of thanks.

without a ~
They did as they were told, without a murmur.

~ of

the murmur of voices

soft | low | distant, far-off

hear

~ of
the distant murmur of traffic

gently, quietly, softly, under your breath
‘What a fool I''ve been,’ he murmured softly.

huskily, thickly, throatily | sleepily | shakily | apologetically, appreciatively, politely, soothingly, thoughtfully
‘Mmm, ’ she murmured appreciatively.

drily, ironically, sarcastically, sardonically, silkily, sweetly
(ironic),

wryly

hear sb
She heard him murmur something under his breath.

to
He held her tight and murmured to her.