What is Voice pedagogy? Pt2

History
Before 17th century, singers were usually untrained, using what natural talents they were able to develop on their own. With the rise of opera and solo song after 1600, talented singers would assist others who needed improvement. Giulio Caccini was known as an important early Italian voice teacher.
In the late 17th and 18th centuries, with the rise in popularity of castrato voice in Italian opera, voice teachers were needed to train the young male singers into highly developed musicians and vocal artists. Pier Francesco Tosi was perhaps the best known castrato teacher. His treatise, Opinioni de' cantori antichi e moderni (1723), translated into English as Observations on the Florid Song, was considered the standard in voice instruction through the 18th century.
Voice teachers in the 19th century continued to train singers for careers in opera. Manuel Patricio Rodríguez García is often considered one of the most important voice teachers of the 19th century, and is credited with the development of the larygoscope and the beginning of modern voice pedagogy.

Examining the vocal mechanism with a laryngoscope, late 19th century
The field of voice pedagogy became more fully developed in the middle of the 20th century. A few American voice teachers began to study the science, anatomy, and physiology of singing, especially Ralph Appleman at Indiana University and William Vennard at the University of Southern California. They developed courses of study for beginning voice teachers, adding these scientific ideas to the standard exercises and empirical ways to improve vocal technique, and by 1980 the subject of voice pedagogy was beginning to be included in many college music degree programs for singers and music educators.

Mathilde Marchesi was both an important singer and teacher of singing at the turn of the 20th century.
More recent works by authors such as Richard Miller have increased the general knowledge of voice teachers, and scientific and practial aspects of voice pedagogy continue to be studied and discussed by professionals. In addition, the creation of the National Association of Teachers of Singing enabled voice teachers to establish more of a consensus about their work, and has expanded the understanding of what singing teachers do.