Escuchar (to listen) indicates an intentional and active understanding or appreciation of sounds such as music or speech. You would use it to say: "I am listening to Bach." "They are listening to his speech." ""We listen when the teacher speaks." Oír (to hear) is not necessarily intentional. It is a sound that reaches our ears and we perceive it; however, we do not intentionally seek an understanding or appreciation of it. We normally do not control it. "I heard the explosion." "Can you hear me?" Comparison: "Nobody hears me." (making a sound) "Nobody listens to me." (attempting to communicate) ¿Podría hacer otra correción? En tu pregunta escribiste: "I them used..." En inglés el complemento "them" se escribe después del verbo. "I used them..." :-)