It's difficult to know since we can't really hold conversations about radio
vs. no-radio with our cats.  However, I am of the opinion that it does
help -- and it certainly can't hurt.  I left a radio tuned (moderate volume)
to "easy listening" or classical radio when Duffy was in a bedroom by
himself during the days when I was introducing him to Holly.  I think they
are used to companionship and think the sound of a radio or TV would help.
This is especially true if the cat is alone (that is, no other cats for
companionship).

MaryL

I'm not sure that anyone can "prove" if a radio helps or not. My
opinion is that it couldn't hurt, as long as it isn't turned on too
loudly.

I always leave the radio on when I go out - only on easy listening stations
though.  Also, our shelters here have a radio on in the cat and dog rooms.  I
can't remember where I read it, but I remember a study was done that found
that animals were soothed by music being on - the #1 soothing sound was
country, #2 was classical.

Riannon

If you were locked in a house by yourself would you like to have a
radio or TV?

Would you prefer a companion?

I think a radio is better than leaving the cat in total silence but no
radio fully compensates for being totally alone.

-mhd