Athomic and Stouts (1970)

Atom-Boy and Atom-Boy And the Thugs (directed by Elbert Tuganov at the Tallinnfilm studio) certainly feature some of Pärt’s most recognised music. The films – fairy tales of the technological age – are about the tiny atomboy Aatomik, who learns how to control his immense power and help people in doing so. There is also a fun story connected to Aatomik’s song in the film. Specifically, Els Himma, who was supposed to sing Aatomik’s parts, was unable to come to the studio on recording day, and so was substituted by Eri Klas – a famed conductor and Arvo Pärt’s good friend. However, viewers have no idea that anything changes, because the song is distorted in the film and played several octaves higher.
Songs from Childhood - Musiksalon - Universal Edition, http://musiksalon.universaledition.com/en/article/songs-from-childhood (29.12.2015).