Hola Paula

Both are correct but it depends on what you really want to say. 

If you want to say that you are listening to music you use escuhar música. However if you mean that you hear music as in you are receiving sounds of music, maybe your neighbours are having a party and you can hear the music that comes from there, you use oír música. 

Here's an article that we dedicated to these two verbs to help understant the difference. 

I hope it's useful. 

Saludos cordiales

Inma