What you’re listening for in music is energy. Yes, music is vibrations and vibrations literally produce energy, but I’m making a more abstract point. You don’t really need to listen to form, or structure, or even melody and harmony to understand what is going on when you’re listening to a song. It’s the energy itself–where it’s going and where it just came from that matters.
Music is the language of energy and it’s telling you things in this language which is transferring that literal energy into your body which produces emotion in you (energy in motion). So how you feel is directly being produced by what you hear. The artist already wrote all the notes. All the music was written to sound exactly as it does in every moment. So, if you’re sitting, thinking about your day or your job or something while you’re listening to music–it’s the equivalent of zoning out while someone is speaking to you.
How attentive to the most specific and subtle details can you be if you’re thinking about something else? Stop thinking altogether. Just listen to the energy.