The early research by B. Szabolcsi and Eric Werner assumed that the Gregorian Psalmody Tonus Peregrinus originated in the Jewish tradition. This article expands the earlier research on that topic. The connection between the Tonus Peregrinus and the Jewish tradition is not in their melodic structure but in the independant motivic units.
Gerson-Kiwi's analyses the different types of polyphonies and uses the polyphonies of Yemenite Jews, Samaritans and Jews of Corfu (Greece) to show that polyphonies exist among ethnicities which were not considered the "polyphonic races"- a theory which was prevalent in the early 20th century. Analysis of the music of the three unrelated groups show different kinds of polyphonic singing.