Estelle Liebling

Estelle Liebling (April 21, 1880 – 1970) was a vocal coach who taught singing using the three-register method. She stressed the "unmusicalness" of the seventh octave, as well as the avoidance of the head register in men. One of Liebling's most famous pupils was Beverly Sills, a coloratura soprano. She also instructed Meryl Streep as a young girl as a singer.
Estelle Liebling had been a pupil of Mathilde Marchesi and carried forth the Manuel Garcia Jr. (Manuel Patricio Rodríguez García) tradition.
Liebling had been a favored soprano of John Philip Sousa earlier in her career.