I couldn't possibly agree more. I will, however, go a bit further and say that music is a very simple yet extremely potent form of magic.
Well, it's because music is much more than background noise. The right song, at the right moment can do so much to a person on many levels. Think about a time when you've been feeling down and just sat down and listened to something that completely blew you away. It hit the right spots and danced on the right nerves and left you feeling better, perhaps even empowered. Many soldiers have said that before going into battle that they will listen to something to get the blood flowing and to keep them cool under pressure. It helps with their focus.
Now, you may be wondering just what the hell this has to do with a horror fiction blog. The answer is, quite a bit. Think about the characters you are writing. The setting. Music can serve in making the scenes much more powerful and help you focus on the emotions you're trying to express.
Now, I know some people don't like to listen to anything while they write. To each their own. Perhaps try a little before you begin your session. Maybe take a five minute break and see what happens. If the lyrics are getting in the way then some instrumentals may do the trick.
During the time I was writing Carcass, I had Sully's Avalon album playing. For Sticks And Stones, it was Disturbed's The Lost Children. Birthday Wish was anything Type O Negative etc.
Lately, I've been listening to Nightwish... a lot. It's really bringing some thing to life!
What do you have playing when you write? If anything at all. Feel free to comment here or on Facebook.