There's a book titled "A Thirty-Year History of Programs Carried on National Radio Networks in the United States, 1926-1956," by Harrison B. Summers that your friend might find useful. Its season-by-season listings include ratings for most programs.
From: David Pierce <[log in to unmask]>
To: [log in to unmask]
Sent: Saturday, August 24, 2013 10:49 AM
Subject: [ARSCLIST] Where to find Radio Ratings?
A researcher friend asked me to inquire if anyone has recommendations about
where to find Hooper ratings for radio programs in the 30s & 40s?
I've checked the magazines of the time, but either there are only
occasional listings, or I'm not using the right search terms.
Thanks for any suggestions.
Media History Digital Library