pipe up phrasal verb informal (see also pipe)
to suddenly say something, especially when you have been quiet until then:
Mum suddenly piped up ‘No!’

[TahlilGaran] Dictionary of Contemporary English ▲

pipe up
to speak unexpectedly.
“I want to be the first female president!” piped up one of the little girls.

[TahlilGaran] English Idioms Dictionary ▲

pipe up
to speak louder
We asked the speaker to pipe up so that we could hear him.

[TahlilGaran] English Idioms Dictionary ▲

pipe up
v., informal To speak up; to be heard.
Mary is so shy, everyone was surprised when she piped up with a complaint at the club meeting.
Everyone was afraid to talk to the police, but a small child piped up.

[TahlilGaran] English Idioms Dictionary ▲