beautiful, fine, good, lovely, pleasant, sweet
She has a beautiful singing voice.

big, booming, loud, ringing, sonorous, stentorian (formal), strong
light, little, small, thin, tiny, weak
low, soft
faint, inaudible, quiet
audible
deep, gravelly, gruff, hoarse, husky, rough
falsetto, high, high-pitched, shrill, squeaky
clear
muffled, muted
harsh, penetrating, scratchy, sharp
nasal
cracked, rasping, raspy, slurred
I could tell from his slurred voice that he'd been drinking.

mellifluous, rich, silky, smooth, velvet, velvety
sing-song
gentle, soothing
cheerful, cheery
friendly, warm
emotionless, matter-of-fact, unemotional
flat, monotone
calm, cool
firm, steady
shaky
urgent
authoritative, commanding
distinctive, unmistakable
familiar
raised
hushed
cold, icy
angry, annoyed
strained, tired
plaintive, sad
serious, stern
funny, silly
baby
annoying
whiny
mocking, sarcastic, teasing
excited
concerned, worried
distant
disembodied
inner
An inner voice told him that what he had done was wrong.

singing, speaking
alto, baritone, bass, contralto, soprano, tenor, treble
female, male
feminine, masculine

hear
I could hear voices in the next room.

raise
She's a teacher who never has to raise her voice to discipline the children.

drop, lower
She dropped her voice to a whisper.
Please lower your voice!

project
Try to project your voice so that the people at the back of the room can hear you.

control
lose
She's lost her voice and won't be able to sing tonight.

strain
find
He swallowed nervously as he tried to find his voice.

imitate, put on
She put on a silly voice as she imitated her boss.

disguise
know, recognize
silence

go up, rise
His voice rose in angry protest.

die away, drift away, drift off, drop, fade, tail off (esp. BrE), trail away, trail off
‘So he won't come … ’ her voice trailed off in disappointment.

be filled with sth, be full of sth
Her voice was filled with emotion.

be laced with sth, be tinged with sth
sound angry, excited, sad, etc.
deepen, harden, soften, thicken
His voice suddenly thickened with emotion.

echo
Her voice echoed through the silent house.

whisper
‘Be quiet!’ a voice whispered in his ear.

hiss, purr
call, call out, cry, cry out
‘Who is it?’ a female voice called out.

scream, shout, yell
She was dimly aware of voices shouting.

bellow, boom, boom out
resonate, reverberate, ring
come from sth
cut through sth, pierce sth
His deep voice cut through the silence.

break, catch, catch in your throat, crack
His voice broke with emotion.
His voice broke (= became a man's voice) when he was 14.

ask
answer, reply
sing
falter, quaver, quiver, shake, tremble, waver
Her voice shook with fear.

drone, drone on
The flat, unemotional voice droned on.

be devoid of sth
be drowned out by sth
carry

coach, teacher
lessons
recognition
the computer's voice recognition capability

mail (usually voicemail), mailbox, message, traffic
synthesizer
acting (= providing voices for animated film characters)
actor (= who provides voices for animated film characters)
command
box (usually voicebox)

in a/your voice
‘Get out!’ she shouted in a shrill voice.
There was fury in his voice as he answered her.

at the top of your voice
I was shouting at the top of my voice but she couldn't hear me.

a babble of voices, a hum of voices, a murmur of voices
They could hear a loud babble of voices coming from the crowded bar.

in good voice (BrE)
She was in good voice (= singing well) at the concert tonight.
The home fans were in good voice (= making a loud noise) before the match. (BrE)

keep your voice down
Please keep your voice down so as not to wake the children.

keep your voice level, keep your voice steady
He managed to keep his voice steady despite his feelings of panic.

voices in your head, voices inside your head
The main character was crazy, hearing voices in his head.

tone of voice
‘Do you have to speak to me in that tone of voice?’ she asked sadly.

critical, dissenting
Dissenting voices at the newspaper are very rare.

lone
a lone voice of dissent

powerful
Powerful voices in the Senate are determined to bring down the president.

distinctive
a writer with a highly distinctive voice

find
Refugees have been unable to find a voice in politics.

add, lend
Many senior politicians have lent their voices to the campaign.

give
The magazine gave voice to hundreds of oppressed factory workers.

listen to

voice of
to listen to the voice of conscience

make your voice heard
a society in which individuals are able to make their voices heard

speak with one voice
The teachers speak with one voice when they demand an end to the cuts.