Why won't publishers listen to your music?
Suppose you compose music and you think your work would be suitable for TV. You've heard that one way to get into the industry is to compose and record what's called 'production music'. So you write to a number of publishers but all you get is the stock response, "Thank you for your message, but we are not looking for new composers at the moment."
They didn't even want to hear your demo. Why would they reject you when you might be the best composer of TV music since Lalo Schifrin/Debbie Wiseman/Marius Constant (names picked from the Audio Masterclass ceremonial hat)?
(Quick note - production music is music for which the rights are pre-cleared. Any TV production company can use it without further permission, on payment of a standard fee.)
The answer has two principal components. The first is that any publisher of production music already has as many composers as they need. In fact, they have too many and they wish they had fewer. It is far easier to adminster a few high-output composers than many composers whose work comes in dribs and drabs.
The second is that even if you are the best composer in the world, a publisher of production music doesn't need you. In fact they don't want you. They want composers who can turn out work of professional quality day-in-day-out. If your work truly is exceptional, then you shouldn't be writing production music. You should be writing to commission, working your way up from daytime shows to prime time to Hollywood movies and an Oscar.
So how do you get in..?
Well in the course of nature, there will come an opportunity every so often. If you're ready with your demo, and it really is appropriate for use as production music on TV, then you may get your shot. It doesn't hurt to contact production music publishers. Just don't expect to get listened to until there's an opening for someone new.