This wonderful relic from the dawn of speech synthesis is a 2-minute recording from Bell Laboratories, first published in 1962, showcasing the work of John L. Kelly and Louis J. Gerstman for the Visual and Acoustics Research Department.  I acquired this 45 RPM soundsheet in 1966, in the 9th grade, when I began working on a speech synthesis system of my own. (I finally made it to the International Science Fair in 1969 with my “acoustic analog of the vocal tract,” which even had a voice-change problem.)  I slurped this from a USB turntable in 2008, conjured an MP3, sold the soundsheet on eBay, then in 2023 edited the file in Audacity to reduce the background noise.

The Bell Labs speech synthesis soundsheet from the early sixties