The Internet, Cable and Satellite has spawned interest of things in media that no one thought would be of that much importance..YouTube has hundreds of TV commercials from as far back as the late 1940's..A whole hobby has grown up around such mundane things as TV Test Patterns, network logos, and Television sign-on and sign-offs..
J. Alan Wall has a website dedicated to TV station sign-offs (and a few sign-ons).Most of these of course are video.Mostly from his home area in the Southern US from the 1980's-2000's..
A friend of Wall's, Jerry Immel, a voiceover artist from Atlanta, has shared a number of MP3 clips (audio clips only, unfortunately) from watching TV in Cleveland and Philadelphia in the mid-late 1950's..These may be the only clips out there of some of these voices..
Cleveland Audio clips include: (dates approximate)
WEWS-5-First sign on December 17, 1947-From WEWS-First 50 years special-Announcer Randy Culver
KYW-3 sign-off 1956 announcer-Gordon Ward (Thinking this might be Friday night-sign-on was 8AM next day)
KYW sign-off 1956 announcer-Tom Field (Almost certainly Saturday Night-sign-on 9AM Next day)
Both KYW-3 sign-offs were preceeded by a catchy jingle:
Edit:Here are the words to the musical jingle
"We're gonna blow our own horn..
sure as your born you'll agree
There's a new look on T-V
That's K--Y--W-Channel 3
Corny isnt it?.But fun though..
WEWS sign-off 1956 announcer Court Stanton
WJW-8 sign-off 1958-Announcer may have been John Fitzgerald-Doesnt say
Others that may be of interest-Mid 1950's
WRCV-3 sign-on Philadelphia's NBC station
WVUE-12 Wilimgton, Delaware (Phila.) Storer owned this station for a time before foolishly letting it go.
WLWC-4 Columbus-with a push to listen to WLW-700 in Cincinnati
WTRF-7 Wheeling, W. Va.
Link to 1950's audio TV sign-offs page
Scroll down a little for the Cleveland audio sign-offs