Wiktionary
vb. 1 (context intransitive English) To speak up, especially in a robust, assertive manner. 2 (context intransitive English) To being singing or playing musical notes on a pipe or similar wind instrument. 3 (context intransitive of wind, etc. English) To begin to blow more vigorously. 4 (context transitive rare English) To call, awaken, or summon, as with a musical instrument.
WordNet
Usage examples of "pipe up".
Since piping is one of our thoughtless habits, one might think that people would pipe up in Josephine's audience too.
You signed your name - or at least half of it on the pipe up there.
The first time he tried to blow glass, his breath had hitched, hed jerked the pipe up, and a fleck of red-hot glass rolled on to his tongue.
Tris sat on a bench to watch as Keth collected his gather and brought the pipe up.
They bound the pipe up against the hull and took the CARM back to Citizens Tree.