To a degree, acting is part of what we do.  I talk a lot about this in coaching sessions, and give an example of a bad actor versus a good actor:

The bad actor “shades” toward the desk as he talks, knowing that the phone is going to ring.
The good actor just says what he has to say, and the stupid phone interrupts him.

When you’re on the radio, the “visual” is created by the listener.  But what you say and the way you sound paints the picture, too.  Be more than just “a voice saying words” or reading something off a computer screen.  Give me something genuine.