They don't do radio like this anymore... Guy Noir, Private Eye. 

Click on the picture for a larger view. 

You can see the sign language interpreters in the lower left.  And in the big view, you'll see paper cups hanging from two of the microphone stands.  The actors hold that up to the mic and talk into it to get the "telephone" effect.  Tom Keith, the sound effects man on the left, creates most of the effects live with props.  To Tom's right are Tim Russell and Sue Scott, the program's regulars.

Another musical act, Beausoleil, from New Orleans.  And you can see the "on the air" sign a llittle better here.  Actually, just the word "AIR" is showing.

And a sing-along for the audience.  Yes, this is how the audience knows all the words, even to the obscure third verse..

the finale