1967: FEDERAL SIGN AND SIGNAL INTERCEPTOR SIREN
In 1967, the Federal Signal Corporation began manufacture of the PA-20A Interceptor siren, which featured a synthesized electronic siren tone. The unit provided three distinct sounds, a microphone for public address, manual operation, and amplification of radio messages.
I had the Federal Signal PA20 in a 1976 Hess Eisenhardt S&S Ambulance with 2 horns that my company used for promotion. During a parade the local police admired how much louder my old sirens where compared to their newer smaller units. – doctordj (2012)
Submitted to NEMSM February 2011, author unknown, additional content by doctordj