Answer:
the first one says that Alberto heard the music the music from the part and left the house
the second one says Alberto heard the music from the party WHEN he left the house
Explanation:
I'm a Spanish speaker :)
Alberto oyó la música de la fiesta y salió de casa.
It's in preterit time
Alberto oía la música de la fiesta cuando salió de casa.
It's in imperfectt tense
