The marimba ( pronunciation (help·info)) is a musical instrument in the percussion family. It consists of a set of wooden bars with resonators. The bars are struck with mallets to produce musical tones. The bars are arranged as those of a piano, with the accidentals raised vertically and overlapping the natural bars (similar to a piano) to aid the performer both visually and physically. This instrument is a type of xylophone, but with broader and lower tonal range and resonators.

The chromatic marimba was developed in Guatemala from the diatonic marimba. Modern uses of the marimba include solo performances, woodwind ensembles, marimba concertos, jazz ensembles, marching band (front ensembles), drum and bugle corps, and orchestral compositions. Contemporary composers have utilized the unique sound of the marimba more and more in recent years.

Marimba bars are typically made of either wood or synthetic material, rosewood being the most desirable. Padouk is commonly used as a more affordable alternative. Bars made from synthetic materials generally fall short in sound quality in comparison to wooden bars, but are less expensive and yield added durability and weather resistance, making them suitable for outdoor use; marimbas with wooden bars are usually played inside because the bars are susceptible to pitch change due to weather. Bubinga and mahogany have also been cited as comparable to rosewood in quality for use as marimba bars. The specific rosewood used is universally from Honduras, Dalbergia stevensonii. This wood has a Janka rating of 2200, which is about three times harder than Silver Maple. The bars are wider and longer at the lowest pitched notes, and gradually get narrower and shorter as the notes get higher. During the tuning, wood is taken from the middle underside of the bar to lower the pitch. Because of this, the bars are also thinner in the lowest pitch register and thicker in the highest pitch register.

Stephen Michael "Steve" Reich ( /ˈraɪʃ/; born October 3, 1936) is an American composer who is one of the pioneering composers of minimal music along with La Monte Young, Terry Riley, and Philip Glass.

His innovations include using tape loops to create phasing patterns (examples are his early compositions, "It's Gonna Rain" and "Come Out"), and the use of simple, audible processes to explore musical concepts (for instance, "Pendulum Music" and "Four Organs"). These compositions, marked by their use of repetitive figures, slow harmonic rhythm and canons, have significantly influenced contemporary music, especially in the US. Reich's work took on a darker character in the 1980s with the introduction of historical themes as well as themes from his Jewish heritage, notably the Grammy Award-winning Different Trains.

Reich's style of composition influenced many other composers and musical groups. Reich has been described, in The Guardian by music critic Andrew Clements, as one of "a handful of living composers who can legitimately claim to have altered the direction of musical history", and the critic Kyle Gann has said Reich "may...be considered, by general acclamation, America's greatest living composer."

John Milton Cage Jr. (September 5, 1912 – August 12, 1992) was an American composer, music theorist, writer, and artist. A pioneer of indeterminacy in music, electroacoustic music, and non-standard use of musical instruments, Cage was one of the leading figures of the post-war avant-garde. Critics have lauded him as one of the most influential American composers of the 20th century. He was also instrumental in the development of modern dance, mostly through his association with choreographer Merce Cunningham, who was also Cage's romantic partner for most of their lives.

Cage is perhaps best known for his 1952 composition 4′33″, which is performed in the absence of deliberate sound; musicians who present the work do nothing aside from being present for the duration specified by the title. The content of the composition is not "four minutes and 33 seconds of silence," as is sometimes assumed, but rather the sounds of the environment heard by the audience during performance. The work's challenge to assumed definitions about musicianship and musical experience made it a popular and controversial topic both in musicology and the broader aesthetics of art and performance. Cage was also a pioneer of the prepared piano (a piano with its sound altered by objects placed between or on its strings or hammers), for which he wrote numerous dance-related works and a few concert pieces. The best known of these is Sonatas and Interludes (1946–48).