The advent of digital radio, the radio that gives listeners audio that sounds as sharp and crisp as a CD, has come off like the proverbial tree that falls in the woods. There was barely anyone around to hear it. That’s because the special receivers equipped to tune in the digital HD Radio technology weren’t being sold in any stores. But that is about to change….

But, in recent weeks, the Good Guys electronics chain has begun selling a $400 Kenwood HD Radio car stereo receiver. And this month, radio stations KFOG- FM and the Bone, which began broadcasting in digital earlier this year, are planning some system giveaways to help promote digital radio.

It’s still a trickle, and the transformation to digital may take a decade or two to fully play out. But radio executives and technology analysts believe it is the dawn of a new era.

“It is the future of radio,” said Dwight Walker, station manager for KFOG and KSAN-FM, called the Bone.