Wave

In physics, a wave is an oscillation accompanied by a transfer of energy that travels through space or mass. Frequency refers to the addition of time. Wave motion transfers energy from one point to another, which displace particles of the transmission medium—that is, with little or no associated mass transport. Waves consist, instead, of oscillations or vibrations (of a physical quantity), around almost fixed locations.

There are two main types of waves. Mechanical waves propagate through a medium, and the substance of this medium is deformed. The deformation reverses itself owing to restoring forces resulting from its deformation. For example, sound waves propagate via air molecules colliding with their neighbors. When air molecules collide, they also bounce away from each other (a restoring force). This keeps the molecules from continuing to travel in the direction of the wave.

The second main type of wave, electromagnetic waves, do not require a medium. Instead, they consist of periodic oscillations of electrical and magnetic fields originally generated by charged particles, and can therefore travel through a vacuum. These types of waves vary in wavelength, and include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

Sheet music

Sheet music is a handwritten or printed form of music notation that uses modern musical symbols to indicate the pitches (melodies) and rhythms of a song or musical piece. Like its analogs – books, pamphlets, etc. – the medium of sheet music typically is paper (or, in earlier times, parchment), although the access to musical notation since the 1980s has included the presentation of musical notation on computer screens. Use of the term "sheet" is intended to differentiate written or printed music from a sound recording, radio or TV broadcast or a recorded live performance, which may capture film or video footage or the performance as well as the audio component. In everyday use, "sheet music" (or simply "music") can refer to the print publication of commercial music in conjunction with the release of a new film, TV show, record album, or other special or popular event which involves music. The first printed sheet music was made in 1473.

Sheet music is the basic form in which Western classical music is notated so that it can be performed by solo singers or instrumentalists or musical ensembles. Many forms of traditional and popular Western music are commonly learned by singers and musicians "by ear", rather than by using sheet music (although in many cases, traditional and pop music may also be available in sheet music form).