Vibrato (Italian, from past participle of "vibrare", to vibrate) is a musical effect consisting of a regular, pulsating change of pitch. It is used to add expression to vocal and instrumental music. Vibrato is typically characterized in terms of two factors: the amount of pitch variation ("extent of vibrato") and the speed with which the pitch is varied ("rate of vibrato").
In singing, it can occur spontaneously through variations in the larynx. The vibrato of a string instrument and wind instrument is an imitation of that vocal function. Vibrato can also be reproduced mechanically (Leslie speaker) or electronically as an audio effect close to chorus.
Terminology
History Descriptions of what would now be characterised as vibrato go back to the 16th century.Martin Agricola, and William E. Hettrick. The “Musica Instrumentalis Deudsch” of Martin Agricola: A Treatise on Musical Instruments, 1529 and 1545. Cambridge Musical Texts and Monographs. Cambridge: Cambridge University Press, 1994; Lodovico Zacconi, Prattica Di Musica. Bibliotheca Musica Bononiensis. Sezione Ii, N. 1-2. Bologna: Forni, 1983; Michael Praetorius, Syntagma Musicum. Documenta Musicologica; 1. Reihe: Druckschriften-Faksimiles. Kassel: Bärenreiter, 1959. However, no evidence exists of authors using vibrato before the 19th century.Christian Friedrich Daniel Schubart, Ideen Zu Einer Aesthetik Der Tonkunst. Wien: Degen, 1806. Instead, authors used various descriptive terms interchangeably, including tremolo, bebung, and tremblement, and descriptions such as wavering, shake and trillo. These “terminological uncertainties”Greta Moens-Haenen, “Vibrato.” Grove Dictionary of Musical Instruments. Oxford University Press, 2015. continue to pervade modern definitions of vibrato.
Vibrato and tremolo
The terms vibrato and tremolo are sometimes used interchangeably, although (in the classical world) they are properly defined as separate effects. Vibrato is defined as a periodic variation in the pitch (frequency) of a musical note that is perceived as one fundamental frequency. Tremolo, on the other hand, is defined as a fast repetition of the same note (usually a semiquaver) or alternation between two notes, especially on instruments which do not have the ability of producing long sustained notes, such as the guitar (for instance tremolo picking).
Human perception Currently, the leading understanding is that when vibrato is utilised, listeners are able to focus on the average pitch and hear it as a single fundamental as opposed to the alternation between two different fundamental frequencies.Nair, Garyth. Voice, Tradition and Technology: A State-of-the-Art Studio. San Diego, Calif: Singular Pub, 1999. Carl Seashore (1967) conducted the first comprehensive studies on perceptions of vibrato in the context of classically trained singers, finding some individuals are 50-100 times more perceptive of the presence of vibrato than individuals with the least ability and that “much of the most beautiful vibrato is below the threshold for vibrato hearing and is perceived merely as tone quality.”Carl E. Seashore, Psychology of Music. New York: Dover, 1967. 46. This conclusion was confirmed by William Vennard (1967) who notes that the listener hears only the average pitch, and the fluctuation is interpreted as enhanced tonal quality.William Vennard, Singing: The Mechanism and the Technic. rev. ed., greatly enlarged ed. New York: Fischer, 1967. 203; Sundberg, “Aspects of Vocal Vibrato”. 59.; Nair. Voice, Tradition and Technology. 180.
In practice, it is difficult for a singer or musical instrument player to achieve only pitch vibrato (where only the pitch is varied), and variations in both pitch and volume will often be achieved at the same time. Electronic manipulation or generation of signals makes it easier to achieve or demonstrate pure tremolo or vibrato.
Acoustic basis The use of vibrato is intended to add warmth to a note. In the case of many string instruments the sound emitted is strongly directional, particularly at high frequencies, and the slight variations in pitch typical of vibrato playing can cause large changes in the directional patterns of the radiated sound. This can add a shimmer to the sound; with a well-made instrument it may also help a solo player to be heard more clearly when playing with a large orchestra.
This directional effect is intended to interact with the room acoustics to add interest to the sound, in much the same way as an acoustic guitarist may swing the box around on a final sustain, or the rotating baffle of a Leslie speaker will spin the sound around the room.
Typical extent of vibrato The extent of the variation in pitch during vibrato is controlled by the performer. The extent of vibrato for solo singers is usually less than a semitone (100 cents) either side of the note, while singers in a choir typically use narrower vibrato with an extent of less than a tenth of a semitone (10 cents) either side. Wind and bowed instruments generally use vibratos with an extent of less than half a semitone either side.
Use in various musical genres Vibrato is sometimes thought of as an effect added onto the note itself, but in some cases it is so fully a part of the style of the music that it can be very difficult for some performers to play without it. The jazz tenor sax player Coleman Hawkins found he had this difficulty when requested to play a passage both with and without vibrato by Leonard Bernstein when producing his record album "What is Jazz" to demonstrate the difference between the two. Despite his technique, he was unable to play without vibrato. The featured saxophonist in Benny Goodman's Orchestra, George Auld, was brought in to play the part.
Many classical musicians, especially singers and string players, have a similar problem. The violinist and teacher Leopold Auer, writing in his book Violin Playing as I Teach It (1920), advised violinists to practise playing completely without vibrato, and to stop playing for a few minutes as soon as they noticed themselves playing with vibrato in order for them to gain complete control over their technique.
In classical music The use of vibrato in classical music is a matter of some dispute. For much of the 20th century it was used almost continuously in the performance of pieces from all eras from the Baroque onwards, especially by singers and string players.
The rise of notionally historically informed ("period") performance from the 1970s onwards has dramatically changed its use, especially in music of the Baroque and Classical eras. However, there is no actual proof that singers performed without vibrato in the baroque era. Notably, composer Lodovico Zacconi advocated that vibrato "ought always to be used".
Vocal music of the renaissance is almost never sung with vibrato as a rule, and it seems unlikely it ever was; however, it should be understood that "vibrato" occurs over a wide range of intensities: slow, fast, wide, and narrow. Most sources in condemning the practice seem to be referring to a wide, slow, perceptible oscillation in pitch, usually associated with intense emotion, whereas the ideal for modern vibrato, and possibly in earlier times as well, was to imitate the natural timbre of the adult singing voice, from which a measure of vibrato (it has since been shown) is rarely absent.
Leopold Mozart’s Versuch einer gründlichen Violinschule (1756), for example, provides an indication of the state of vibrato in string playing at the end of the baroque period. In it, he concedes that “there are performers who tremble consistently on each note as if they had the permanent fever”, condemning the practice, and suggesting instead that vibrato should be used only on sustained notes and at the ends of phrases when used as an ornament. This however, does not give anything more than an indication of Mozart's own personal taste, based on the fact that he was an educated late Rococo/Classical composer. Mozart acknowledges the difference between the heavy, ornamental vibrato that he finds objectionable, and a more continuous application of the technique less obtrusively for purposes of improving tone quality (in which case he does not refer to it as "vibrato" or "tremolo" at all; describing it as merely an aspect of correct fingering). In this respect he resembles his contemporary, Francesco Geminiani, who advocated using vibrato "as frequently as possible" on short notes for this purpose. Although there is no aural proof, as audio recordings were not around for more than 150 years, that string players in Europe did not use vibrato, its overuse was almost universally condemned by the leading musical authorities of the day.
Certain types of vibrato, then, were seen as an ornament, but this does not mean that it was used sparingly. In wind playing too, it seems that vibrato in music up to the 20th century was seen as an ornament to be used selectively. Martin Agricola writing in his Musica instrumentalis deudsch (1529) writes of vibrato in this way. Occasionally, composers up to the baroque period indicated vibrato with a wavy line in the sheet music. Again, this does not suggest that it was not desired for the rest of the piece any more than the infrequent use of the term in 20th-century works suggests that it is not used elsewhere.
Vibrato wars Music by late-Romantic composers such as Richard Wagner and Johannes Brahms is now played with a fairly continuous vibrato. However, some musicians specialising in historically informed performances, such as the late conductor Roger Norrington, argue that it is unlikely that Brahms, Wagner, and their contemporaries would have expected it to be played in this way. This view has caused considerable controversy. The view that continuous vibrato was invented by Fritz Kreisler and some of his colleagues is held to be shown by early sound recordings, which allegedly demonstrate that this profuse use of vibrato appeared only in the 20th century.
The alleged growth of vibrato in 20th-century orchestral playing was traced by Norrington by studying early audio recordings but his opponents contend that his interpretations are not supported by the actual samples. Norrington asserted that vibrato in the earliest recordings is used only selectively, as an expressive device; the Berlin Philharmonic Orchestra were not recorded using vibrato comparable to modern vibrato until 1935, and the Vienna Philharmonic Orchestra not until 1940. French orchestras seem to have played with continuous vibrato somewhat earlier, from the 1920s.
Defenders of vibrato claim that the sonic limitations of 78-rpm recordings, particularly with respect to overtones and high frequency information, make an uncontroversial assessment of earlier playing techniques difficult (although, it must be said, early recordings of operatic singers manage to show clearly the extent to which a vibrato is present [or not] in their voices). Moreover, defenders of vibrato maintain that a distinction needs to be made between the kind of vibrato used by a solo player and the sectional vibrato of an entire string ensemble, which cannot be heard as a uniform quantity as such, but rather, it manifests itself in terms of the warmth and amplitude of the sound produced, as opposed to a perceptible wavering of pitch. The fact that, as early as the 1880s, composers such as Richard Strauss (in his tone poems "Don Juan" and "Death and Transfiguration") as well as Camille Saint-Saëns (Symphony No. 3 "Organ") asked string players to perform certain passages "without expression" or "without nuance" somewhat suggests the general use of vibrato within the orchestra as a matter of course; by the same token, indications by Mahler and Debussy that specifically demand the use of vibrato in certain passages may suggest the opposite practice.
In Baroque music