I just now got around to reading the linked article, and I read it as specifically about music--musicophilia--more than voices, although I guess sometimes it's voices singing.

As far as voices in the head go, and especially having conversations with them, I think that's actually a pretty normal and healthy thing. It's our primate brains, and their "theory of mind" that lets everyone build up mental models of other minds. It gives us the survival-positive ability to predict what other humans will do, and find ways to manipulate them to get our own way.

The strongest voices--mental models--generally come from our parents, naturally. When people aren't conscious of it, they tend to think like their parents. When they notice it, they often think more independently, or even in opposite ways.

We can build up models of people we spend some time with. I don't have to post on the Zone to argue with Tom--I can argue with VirtualTom™ any time I want.

I use it professionally, to good advantage. For example, last year I spent several months working with a high-powered Software Architect (for the non-geeky: Software Architects are at the top of the food chain. They don't tell lesser programmers what to do, they tell them how to do it. They're the creators and keepers of dogma like Object-Oriented Programming). Over the course of several months, I internalized a pretty good model of "Olivia" (psuedonym) and her way of thinking, and nowadays as I work, I often run designs by VirtualOlivia and get "her" feedback. Such a model can't provide any information I don't already know, of course, but it gives me another viewpoint, a "parallax view", to augment my own. It's a little bit of extra brainpower borrowed from "Olivia".

Part of the reason I get a little embarrassed when people tell me I'm smart is that I feel like I should really credit an ensemble of such mental models, rather than any native gift. Parents, relatives, caregivers, teachers, coworkers, mentors, authors, and a whole horde of others, have taught me to think by contributing models. I wasn't born knowing how to think, I needed a whole lot of transplants to bootstrap my mind.

People freak out sometimes when they hear those voices. But I don't think there's much power in denying their reality and saying they're hallucinations. Granting their reality, and understanding where they're coming from, I think gives people the power to evaluate what they're saying, compare the advice to core internalized standards, and choose whether or not to take the advice. Listen to the whole chorus and try to discern the consensus in what they're saying.

Don't be afraid of the voices in your head, bunky. They may not necessarily be your friend, but they're not evil spirits out to get you either. They're just virtual shades of other people.