quaver

nouns

a tremulous sound
quaver
is a type of (narrower)
the sudden occurrence of an audible event
"the sound awakened them"
sound
a musical note having the time value of an eighth of a whole note
eighth note, quaver

verbs

give off unsteady sounds, alternating in amplitude or frequency
quaver, waver
sing or play with trills, alternating with the half note above or below
quaver, trill, warble