Christian Saint-Preux Langlade is a french pianist, composer and conductor born in 1950.
This piece, composed in 1969 was very famous in the 70ties. Several millions of copies have been sold.
"Concerto pour une voix" (concerto for one voice) is both the name of the piece and the name of the lp album.
Obviously, It's not a concerto at all, but an "air", for soprano (in vocalise mode), piano and string orchestra. Here is a link to the original music : https://www.youtube.com/watch?v=8NOBBvQRT-w
Like many music of this period, it's a cross-over between classical music and pop, often labeled "easy listening".
As a young child, I heard this tape hundreds of times in my parent's car, during long rides, so it was a real nostalgic pleasure to make this transcription.