quiet
damped
dampened
deadened
echoless
hush
hush as death
hushed
inaudible
mousy
muffled
mute
muted
quiescent
silent
soft
soundless
still
still as death
stilly
subaudible
unarticulated
unhearable
unpronounced
unsounded
unuttered
unvocalized
unvoiced
whist
brisk
catlike
cautious
deft
effortless
frantic
hesitant
leisurely
lithe
purposeful
rhythmic
sinuous
steady
stealthy
tranquil
unhurried
upward