To give up or admit defeat because one can't bear the hardship or difficulty; a colloquial idiom (also said as 根を上げる).
忙しさに音を上げて、彼はプロジェクトを辞めてしまった。
Overwhelmed by the workload, he gave up and quit the project.
子どもが夜泣きに音を上げて、両親は疲れ果てていた。
The parents were exhausted, having given up because the baby kept crying at night.
何度説明しても理解しない学生に音を上げることはできない。
I can't afford to give up on a student who doesn't understand even after repeated explanations.