to hear : the action of hearing is one of the 5 senses that happen without deliberate intention from you , as Loren said , you hear a noise , you don't intentionally decide to do any effort with your sense to perceive the noise or the voice and usually the thing you hear is short termed and instant . He heard a voice coming from the other room . to listen : the action of deliberately and intentionally using your sense of hearing to perceive an audible context and usually you listen to longer term material , like conversation , song , radio etc He likes to listen to music .

Como ya te han dicho To listen es mas apropiado cuando quieres decir que estas escuchando algo, y cuando dices To hear es simplemente cuando oyes algo.. Like in I want to listen to my new CD. I heared an strange sound.

oir- to hear escuchar- to listen

To listen is like when you are talking to someone and they aren't paying attention to you. You would say , "Listen to me." To hear is like when you hear a noise. "I heard a noise in the attic."