The rhythm of the write.
Finding your natural rhythm when writing is key to discovering your voice, and you better be honest with yourself and look in the right place to find it.
Many writers listen to music while writing, and there is a perfectly good reason for it: It makes it easier for them to get into the rhythm of their writing.
Personally, I have always liked the natural rhythm of my voice better. If I listen to music while writing it doesn't work as well, as if I write in silence.
But that's me. I like the natural rhythm of life and try to avoid any extra layers of noise. I don't listen to music when driving either, because I enjoy listening to the sound from the engine and the wind around the car.
That doesn't mean it's wrong, but merely that adding something artificial to the situation isn't how I find my rhythm.