聞こえる
きこえる · kikoeru · JLPT N4 · verb-ichidan
to be heard
👂 聞 (hear) + える (can be) = sound reaches you on its own: to be audible
Same kanji as 聞く (kiku, to listen), but the -eru ending makes it spontaneous: you are not trying to listen, the sound simply arrives. Kiku = I listen; kikoeru = it can be heard. The thing heard takes が, not を.