Karle was born Theo Karle Johnston. He had a typical American career start singing in churches and oratorio performances.
After becoming known, in the US, as a concert singer, he went to Paris to further study.
As a result
Karle made his debut at the Opéra-Comique (16 September 1927 as Almaviva, then
Cavaradossi). He was active in France from 1927 to 1930 mainly at the Opéra-Comique and at the
Monte Carlo Opera. This is very probaly wrong as Welsh's book
on the Monte Carlo Opera does not list him as having sung there..
He came back to the US in 1930 and was a big star until 1934 at the Columbia
Broadcasting Radio System.
Since 1933, he taught singing at the New York School of Vocal Art while continuing his
concert career.
He was the tenor of a well known vocal quartet composed, besides him, of
Marie Tiffany, Lennox and Richard Bonelli.
He recorded before his departure for France for Brunswick and Victor.
Reference: Kutsch and Riemens
