A groppo or gruppo is a specific type of cadential trill which alternates with the auxiliary note directly above it and ends with a musical turn as additional ornamentation.
[8] In the baroque period, a number of signs indicating specific patterns with which a trill should be begun or ended were used.
Several trill symbols and techniques common in the Baroque and early Classical era have fallen entirely out of use, including for instance the brief Pralltriller, represented by a very brief wavy line, referred to by Carl Philipp Emanuel Bach in his Essay on the True Art of Playing Keyboard Instruments (Versuch) (1753–1762).
However the lip trill is often still used in the modern French horn in places where the harmonics are only a tone apart (though this can be difficult for inexperienced players).
Vocal music of the classical tradition has included a variety of ornaments known as trills since the time of Giulio Caccini.
However, by the time of the Italian bel canto composers such as Rossini, Donizetti and Bellini, the rapid alternation between two notes that Caccini describes as a shake was known as a trill and was preferred.
Coloratura singers, particularly the high-voiced sopranos and tenors, are frequently required to trill not only in the works of these composers but in much of their repertoire.
Opinion is divided as to if and how well a trill can be taught or learnt, though mezzo-soprano Marilyn Horne frequently stated that she gained her trill by a commonly taught exercise, alternating between two notes, starting slowly and increasing velocity over time.
[10] The director of the Rossini Opera Festival, Alberto Zedda has opined in interview that the "widespread technical deficiency",[11] the inability to trill, is a source of "frustration and anguish".
However, in early music some refer to a related ornament specifically called trillo: Trillo is the least familiar of the vocal maneuvers, and, in present day usage, is performed either on a single note or as a technique for executing rapid scale-like passages.
Perceptually, it is heard as a rhythmic interruption, or near interruption, of phonation that typically begins slowly with individual pulses separated by a short silent period and then often increases in rate to something resembling a vocal imitation of machine gun firing, albeit without the accompanying cacophony.