"들을까요"라는 것 맞아요 :)

들을까요? is correct 그는 아무 소리도 들을 수 없었다. 지각을 했으니 꾸지람을 들을 게 뻔했다. 지각하면 선생님에게 꾸지람을 들을 거야.

듣다 is a ㄷ irregular verb. If a verb is a ㄷ irregular verb, the ㄷ changes to ㄹ when followed by a vowel. like 듣다 -> 들어요. So, 들을까요? is correct. Differentiating ㄷ irregular verbs is very tricky. It depends on both spelling and meaning at the same time. Here is a list of ㄷ irregular verbs. 걷다(to walk) 깨닫다(to perceive) 닫다(to run fast)(rarely used) *** 닫다(to close) is a regular verb. 듣다(to listen) 묻다(to ask) *** 묻다(to bury) is a regular verb 붇다(to swell) 싣다(to load) 알아듣다(to understand) 치닫다(to rush up) 캐묻다(to interrogate)