[The] flexatone [is a] percussion instrument; shaking it causes two wooden balls, one on either side, to strike a metal blade subject to thumb pressure, which thereby can produce spooky glissando effects.
An invention for a flexatone occurs in the BritishPatent Records of 1922 and 1923. In 1924 the 'Flex-a-tone' was patented in the USA by the Playatone Company of New York. "An instrument called the 'Flex-a-tone' was patented in the U.S.A. in 1924 by the Playertone Company of New York. It was introduced as a new instrument, making 'jazz jazzier' and announced as combining the tone effect of musical saw, orchestra bells, and song whistle." "Small sheet of spring steel in a frame with wooden strikers mounted on either side. The player shakes the beater while bending the steel in order to change the pitch."
The instrument was first used in 1920s jazz bands as an effect but is now mainly and rarely used in orchestral music.
The flexatone is a small, thin, flexible metal plate fastened to its frame at one end. The plate is hit alternatively on each side by rubber or wooden beaters mounted on a clock spring. A tremolo is the normal effect, and thumb pressure on the free end of the plate alone changes the pitch, resulting in a glissando from note to note...It is usually employed as an abstract effect, since it is notoriously difficult to play specified pitches with any accuracy--the thumb pressure to sharpen or flatten is extremely subtle and difficult to gauge...The sound is quite clangy, a cross between the smoothness of a musical saw and a poor glockenspiel.
Wooden knobs mounted on strips of spring steel lie on each side of the metal sheet. The player holds the flexatone in one hand with the palm around the wire frame and the thumb on the free end of the spring steel. The player then shakes the instrument with a trembling movement which causes the beaters to strike the sides of the metal sheet. While shaking the handle, the musician makes a high- or low-pitched sound depending on the curve given to the blade by the pressure from his or her thumb: "As the thumb depresses the vibrating metal sheet, the relative pitch of the instrument ascends; as the thumb pressure is released, the relative pitch of the instrument descends." A vibrato is thus produced. While the instrument has a very limited dynamic range, volume can be controlled by how vigorously or delicately the player shakes the Flexatone.
It cannot be pretended that its scope or range are wide, but such as it is, it is quite irreplaceable. Its curious penetrating whine is created by rapid oscillation of the little wooden knob at the end of the thin flexible strips against the broad curving metal plate, whose curvature--and hence pitch--is controlled by the thumb. This effect cannot be emulated by any other means except possibly the Ondes Martenot...or perhaps the musical saw.
"Vibes generally make a perfectly acceptable alternative, especially when the music is somewhat indeterminate anyway."
An alternate technique involves removing the two wooden knobs and their mounting springs, and then using a small metal rod (e.g., a triangle beater) held in the free hand striking the strip of spring steel. The pitch is altered in the same manner as the previous technique. "This method give the player greater control of the sound of the flexatone as it eliminates the need to shake the instrument." This method of playing results in a different, more constrained sound. The flexatone may also be bowed along its edge with an orchestral string instrument bow.
The flexatone is notated using tremolo lines (rolls) to indicate shaking the instrument and lines to indicate the desired direction of the glissando or a wavy line (chevron) to indicate alternating thumb pressure. If using the instrument with the balls removed, indicate strikes with single notes followed by arrows indicating the direction of the glissando (similar to a guitar tab pitch bend). It is recommended that pitch designation should only be approximate, as, "specific pitches are difficult but possible; glissandi without specific pitch are easily executed."
The flexatone is sometimes heard in funk music, and occasionally in pop music for special effect. It is occasionally used in the soundtracks of films or cartoons to represent "ghosts" or other paranormal phenomena.
^ abKalani (2008). All About Hand Percussion: Everything You Need to Know to Start Playing Now!, p.27. "The flexatone is primarily use as a sound effect, often heard in classic cartoon sound tracks. The sound of this instrument can be compared to that of the musical saw, a 'flexible' tone that changes smoothly in pitch." ISBN9780739049648.
^ abHolland, James (2005). Practical Percussion: A Guide to the Instruments and Their Sources, p.23-4. ISBN9781461670636. "Perhaps the most famous example is probably still Khachaturian's Piano Concerto (1946)...However, when Khachaturyan came to the London Symphony Orchestra in the early 1970s he immediately ruled out the flexatone on sight, before a note had been played, and wanted a musical saw or nothing! Just how the flexatone came to appear in the score in the first place remains a complete mystery."
^ abcDel Mar, Norman (1983). Anatomy of the Orchestra, p. 427-8. University of California. ISBN9780520050624. Right after mentioning that, "the latter [the musical saw] is orchestrally wholly unknown," he mentions Khachaturian's use of the flexatone in his Piano Concerto.
^Spratt, Geoffrey K. (1987). The Music of Arthur Honegger, p.124. Cork University. ISBN9780902561342. Act 2, Scene VIII, "opens with a long treble melismatic line of quite astounding expression and profundity--qualities in no small way attributable to its scoring for saxophone and musical saw."
^ abNardolillo, Jo (2014). All Things Strings, p.90. Scarecrow. ISBN9780810884441. "Khachaturian included a musical saw in the score for his first piano concerto, a part now usually played by a violin."
^Conway, David (2004). "Gogol in St. Petersburg", SocialAffairsUnit.org.uk. Report of a performance of "The Nose" in St. Petersburg 2004: "intriguing duet for balalaika and musical saw".
^Woodstra, Chris; Brennan, Gerald; and Schrott, Allen; eds. (2005). All Music Guide to Classical Music, p.1180. Hal Leonard. ISBN9780879308650.
^Dixon, Gavin (2016). Schnittke Studies, unpaginated. "The flexatone is a percussion instrument, only seldom used in classical music...often in satirical and groteque musical contexts." Routledge. ISBN9781317059226.
^Albright, Daniel; ed. (2004). Modernism and Music: An Anthology of Sources, p.194. "Genesis 1:3. In Kol Nidre (1938), Schoenberg set the words 'Let there be light' to an amazing sound flash from a flexatone." University of Chicago. ISBN9780226012674.