''Squillo'' is the resonant, trumpet-like sound in the voices of opera singers. It is also commonly called "singer's formant", "ring", "ping", "core", and other terms. ''Squillo'' enables an essentially lyric tone to be heard over thick orchestrations, e.g. in late Verdi, Puccini and Strauss operas. Achieving a proper amount of ''squillo'' in any performing context is imperative: too much and the tone veers towards the shrill; too little and the purpose of the ''squillo'' cannot be achieved. ''Squillo'' is recognizable by a distinctive brilliant, ringing quality in the timbre of the voice. This perception is caused by the presence of a peak in the 2 - 5 kHz frequency range, to which the human ear is particularly sensitive. The amplification of these particular harmonics is believed to be a result of a narrowing of the Aryepiglottic fold just above the larynx. Voices with naturally acquired ''squillo'', i.e. having naturally strong higher

formants In speech science and phonetics, a formant is the broad spectral maximum that results from an acoustic resonance of the human vocal tract. In acoustics, a formant is usually defined as a broad peak, or local maximum, in the spectrum. For harmonic ...

, are especially prized in opera because they allow a singer to sustain lyric qualities such as limpid high notes, and consistency of tone throughout the vocal range, even in dramatic singing. Voices with ''squillo'' are also easier to record. Uses of the ''squillo'' include: * projecting a small timbre e.g. Tito Schipa, Bidu Sayao * underscoring a dramatically important passage e.g. ''No, non voglio morir'' in ''Sola, perduta abbandonata'' from Puccini's

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* singing through a thickly textured orchestration, e.g. the final bars of ''Libera me'' from

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, in which a soprano has to compete against a ''tutti'' orchestra and full chorus * supporting a pianissimo note floated over an orchestra (which also demands a secure breath control) e.g.

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* supporting a long trill e.g. Joan Sutherland * simulating a scream without compromising the timbre, especially in a verismic opera (albeit that a

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scream is sometimes used in opera, e.g. Tosca's jump to death in

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) * giving an impression of 'youth' to an aged voice, mainly via a cultivation of the head register (cf. Section IX ''Meine Gesangskunst'', by Lilli Lehmann; exemplified vocally by Mirella Freni) Singers known for their mastery of this technique have included

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Kirsten Flagstad Kirsten Malfrid Flagstad (12 July 1895 – 7 December 1962) was a Norwegian opera singer, who was the outstanding Wagnerian soprano of her era. Her triumphant debut in New York on 2 February 1935 is one of the legends of opera. Giulio Gatti-Casaz ...

Giuseppe di Stefano Giuseppe Di Stefano (24 July 19213 March 2008) was an Italian operatic tenor who sang professionally from the mid-1940s until the early 1990s. Called Pippo by both fans and friends, he was known as the "Golden voice" or "The most beautiful voic ...

Jussi Björling Johan Jonatan "Jussi" Björling ( , ; 5 February 19119 September 1960) was a Swedish tenor. One of the leading operatic singers of the 20th century, Björling appeared for many years at the Metropolitan Opera in New York City and less frequentl ...

and

Luciano Pavarotti Luciano Pavarotti (, , ; 12 October 19356 September 2007) was an Italian operatic tenor who during the late part of his career crossed over into popular music, eventually becoming one of the most acclaimed tenors of all time. He made numerou ...

. Some dramatic singers may also employ ''squillo'' rather than volume in the course of a performance, for example

Birgit Nilsson Märta Birgit Nilsson (17 May 1918 – 25 December 2005) was a celebrated Swedish dramatic soprano. Although she sang a wide répertoire of operatic and vocal works, Nilsson was best known for her performances in the operas of Richard Wagner a ...

References

{{opera terms Singing techniques Italian opera terminology