Hum

120 clues
Buzz
Purr
Drone
Bustle
Murmur
Attila
Be busy
Run well
Bee sound
Top sound
Drum head?
Low sound?
Hive sound
Run nicely
Low murmur
Use kazoos
Fan noise?
Motor sound
Go smoothly
Drum intro?
Motor noise
Almost sing
Use a kazoo
What fans do
Engine sound
Engine noise
Run smoothly
Apiary sound
Copier sound
Fridge sound
Play a kazoo
Ho's partner
Beehive sound
Droning sound
Drum starter?
Emulate a bee
Ho's follower
Machine sound
Theme, Part 2
Work smoothly
Sing, in a way
Rhythmic sound
Lyricless song
Sound of a fan
Play the kazoo
Drone — stink
Sing sans words
Vibration sound
Sing wordlessly
Background noise
Proceed smoothly
Forget the words
Had smash "Stars
Operate smoothly
Persistent sound
Be busily active
Electronic noise
Continuous sound
Be busy, as a bee
Indistinct murmur
Sound before drum
Engine room noise
Sound of activity
Good engine sound
Sound happy, maybe
Refrigerator sound
Refrigerator noise
Low, droning sound
Sing without words
Chug along smoothly
How to play a kazoo
Smell badly (slang)
Vocalize on a kazoo
Smooth engine sound
White noise, perhaps
Wordless vocal music
Bustle with activity
Low monotonous noise
Make music on a comb
Sound system problem
Sing with closed lips
Air conditioner noise
Sing with lips closed
How to play the kazoo
Word with drum or bug
Air-conditioning sound
Dinger or drum starter
Sing with closed mouth
Sing with mouth closed
Smooth machinery sound
Be at a loss for words?
Forget the words maybe
Annoying speaker problem
Forget the lyrics, maybe
Sign of smooth operation
Sing with a closed mouth
Well-tuned engine output
Sing without using words
U2 album "Rattle and ___
Good noise from an engine
Proceed without the words
Rattle and ___" (U2 album)
Accompany musically, maybe
Continue without the words
Run smoothly, as a machine
Sing with one's mouth shut
Symptom for a car mechanic
Carry a tune without words
Run smoothly, as an engine
Machine's low, steady sound
Downward Is Heavenward" band
Sing with one's mouth closed
Sound of a well-tuned engine
Fail to know the words, maybe
Sound of tires on the highway
Participate without the lyrics
Substitute for forgotten words
Fake the vocals in Rock Band, say
What you can do if you don't know the words
What to do when you don't know the words to a song
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