hum and haw
hum
noun[ Cusually singular ]
uk /hʌm/ us /hʌm/
a continuous low noise: 持续低沉的噪音;嗡嗡声
hum ofOur house is on a main road, so we can hear the constant hum of traffic.我们的房子在大路旁，所以能听见持续不断的交通噪声。
There's an annoying hum on this computer.这台计算机总是发出一种让人心烦的嗡嗡声。

SMART Vocabulary: related words and phrases

Sounds made by objects, movement or impact
bang around
bleep
boop
choo-choo
chuff
clap along
click away
honk
peal
resonance
rumble
spit
squeak
susurrus
swoosh
thrum
thunk
tick-tock
ticking
whisper

hum | American Dictionary

hum
verb[ I/T ]
us/hʌm/-mm-
to make a continuous, low sound, or to sing a tune with closed lips:
[ I ]Debbie always hums to herself when she listens to music.
[ T ]I’ve forgotten how that tune goes – could you hum it for me?
fig. If something is humming, it is very busy and full of activity:
[ I ]Factories that make paper products are humming at 97% of capacity.
hum
noun[ Cusually sing ]
us/hʌm/
a continuous, low sound:
We could hear the constant hum of traffic outside the window.

Examples of hum

hum
They might be eating, talking, whistling, humming, smoking during the most dramatic scenes.
Although cars stream by, pedestrians lose the impetus to move forward, derailed by this cool pool of sound with its mysterious, chantlike hum.
If a tort system were a stereo system, the cognitive bias would be the hum or hiss, not one of the instrumental tracks.
The precomputed lighting gives a huge lift in architectural quality; and ambient sounds such as bird song and air-conditioning hum strengthen the experience even further.
Intermittent cross-fertilization has kept all these fields humming!
She hummed phrases to herself and subsequently searched for the corresponding notes on the piano.
But when the tune begins to sound like an advertising jingle, one hopes economists would not merely hum along.
Temporal organization of flowering among the humming bird food plants of a tropical wet forest.
In parallel, the vibration or hum from wind turbines discourage their inclusion as part of building structures for human occupation.
Technical equipment from research facilities, as well as ventilation systems, creates a continuous hum that is partly airborne and partly structurally carried.
A jugular venous hum always disappears in die recumbent position and should, therefore, never be confused with a continuous murmur from a duct.
And he started to hum as he offered aperitifs.
In their installation, autonomous robots react to visitors by humming sad or happy music, and by moving in a particular manner.
The bird-scaring tape hums in the wind and was attached in several strands like a bow harp.
He hums - that's the nicest thing about the role.
See all examples of hum
These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors.