The Lettera 22 got its own LP in 1959: Musica Per Parole.
I found this photo on the site of Sara Pavan: http://habitatolivetti.blogspot.nl. Her thesis about the Olivetti company sounds interesting enough, but my Italian is unfortunately not sufficient.
Sound bites of Musica Per Parole are here: http://fonoteca.museocinema.it/fonoteca/disco/1251.
Got to find a copy – the LP is the same size as the Lettera!