Outside the “Peruvian nightingale“ Yma Sumac and her unique and phenomenal “double-voiced trill“ (in “Chuncho“), the “highest“ singers were “the German nightingale“ Erna Sack, and the French “stratospheric colaratura“ Mado Robin. Both sopranos could reach easily C above high C, but the latter could emit even higher and incredible notes, and always clearly and powerfully. Listen to those extracts from “Frühlingsstimmen“ (“Voices of spring“) and “Carnival of Venice“ and prick up your ears!