Treatises on performance practice written during the Baroque period offer several observations of the Baroque perception of vibrato. Descriptions of prominent Baroque singers also serve to clarify our view of historical performance. Here are some of Neumann's findings: (11)
On String Vibrato:
--Basset, 1636. Observes that vibrato ("violent shaking of the hand") was not used frequently, and the lack thereof was in reaction to its overuse by the older generation. -from Harmonie universelle
--Tartini, 1750. Shows that the speed of the vibrato can be varied according to affekt. -from Regole per...il violino
--Christopher Simpson, 1659. Calls the vibrato a "close shake", describes it as "feminine", used to express love or sorrow. -from Division-Violist
--Johan Cruger, 1654. "It would be more praiseworthy and more agreeable to the listener if on the violin they would make use of a steady, sustained, long bowstroke together with a fine vibrato." -from Synopsis Musica
--Leopold Mozart, 1756. Vibrato can be graceful on long notes, but to avoid players who "tremble on every note, as if they had the permanent fever." -from Versuch einer...Violinschule
On Vocal Vibrato:
--J.A. Hiller, 1780. Observes that the castrato Carestini used vibrato "frequently and with very fine effect". -quoted in Moens-Haenen, Das vibrato..., 214)
--Georg Quitschreiber, 1598. "...one sings best with a quivering voice..." -quoted in Moens-Haenen, Das Vibrato..., 158)
--Praetorius, 1614. "...that a singer possess a beautiful, lovely, trembling and wavering voice" -from Syntagma musicum
Finally, Neumann's frequently used letter written by W.A. Mozart in 1778:
"The human voice vibrates by itself, but in a way and to a degree that is beautiful--this is the nature of the voice, and one imitates it not only on wind instruments, but also on strings" -from The Letters of Mozart and his family, trans. Emily Anderson
While the exact size, width, and type of the vibrato to which Mozart was referring is unknown, his description of vibrato as part of "the nature of the voice" seems to support not only the "provibrato" views of Donington and Neumann, but the views of Kelly on continuous vibrato as well. Perhaps Mozart would have supported Kelly's claim that continuous vibrato happens naturally as the voice develops and should not, therefore, be supressed.
On the whole, these findings raise some interesting points. The mere fact that vibrato was discussed and disagreed upon among scholars attests to the fact that it is historically "accurate" in performance. Also, the frequent mention of "trembling, quivering" voices suggests that, although it is vague as to how much, easily perceptible vibrato was present in Baroque vocal performance. Finally, the recurring mention of vibrato being used on long notes for expressiveness cannot be ignored. What some present-day scholars have failed to focus on is the possibility that a perceptible vibrato should be employed mainly on longer notes, such as the messa di voce, for expressive purposes. The shorter notes, melismas, etc. may simply require a straighter tone for the practical purpose of distinguishing each note.
11. All as quoted in Neumann's Performance Practices of the Seventeenth and Eighteenth Centuries, pp. 500-508