3D technology applicable to radio or just tv?

Of course! Now you can hear in 3 DIMENSIONS! /end blatant sarcasm

The audio equivalent of video 3D already exists: it's called Surround Sound.

Your eyes are designed to see forward so that you get a 3D image created by your brain. This is so that you can judge distances accurately and was a great help to your ancestors when they hunted mammoths. To re-create a true 3D image on a 2D device like a tv set is very difficult.
At the moment it is NOT possible to do it without wearing glasses. What you do wear is polarising glasses so at least the colours are ok. That's an improvment on the old style red/blue glasses.

The problem remains that for the best 3D affect you have to sit right in front of the sit. That's tough for viewers off to one side out of the golden angle of view.

Your ears are situated at the sides of your head so that you can get a sense of the spatial relationships of yourself and any potential threats around you. This means that you have a sense of hearing things behind you. That's why Surround Sound in cinemas and the better home HiFi systems works.

We have it already, it's called Stereo sound.