The definition of the word "music" is hotly contested, not least because the word has such strong connotations and use beyond the subject itself.
Music as sound: One common definition of music is to label it as "organized sound" or more ornately, "the artful organization of sound and silence". This definition is widely held to from the late 19th century forward, which began to scientifically analyze the relationship between sound and perception.
Music as subjective experience: Another commonly held definition of music holds that music must be "pleasant" or "melodic". This view is used to argue that some kinds of organized sound "are not music", while others are. Since the range of what is accepted as music varies from culture to culture and from time to time, more elaborate versions of this definition admit some kind of cultural or social evolution of music. This definition was the predominant one in the 18th century, where, for example, Mozart stated that "music must never forget itself, it must never cease to be music."
Music as a category of perception: Less commonly held is the cognitive definition of music, which argues that music is not merely the sound, or the perception of sound, but a means by which perception, action and memory are organized. This definition is influential in the cognitive sciences, which search to locate the regions of the brain responsible for parsing or remembering different aspects of musical experience. This definition would include dance. The Boulanger's established a school of thought centered around this concept which included the idea of eurythmics, which is gesture guided by music.
Music as a social construct: Post-modern theories argue that, like art, music is defined primarily by social context. According to this view, music is what people call music, whether it is a period of silence, found sounds, or performance. Famously John Cage's work 4' 33" is rooted in this conception of music.
Because of this range of definitions, the study of music comes in a wide variety of forms. There is the study of sound and vibration or acoustics, the cognitive study of music, the study of music theory and performance practice or music theory and ethnomusicology and the study of the reception and history of music, generally called musicology.
The commonly defined compositional and auditory aspects of music are pitch, timbre, intensity, and duration. Pitch is rooted in the frequency of the sound experienced, and is perceived as how "low" or "high" a sound is, and may be further described as definite pitch or indefinite pitch. Timbre is the quality of a sound, determined by the fundamental and its spectra: overtones or harmonics and envelope, and varies between voices and types and kinds of musical instruments, which are tools used to produce sound. Intensity, or dynamics, is how loud or quiet a sound is and includes how stressed a sound is. The spatial location or the movement in space of sounds may also be an aspect of music. Silence is also often considered an aspect of music, if it is considered to exist. Duration is the only aspect common to both "sound" and "silence", being the temporal aspect of music. A musician is someone who performs, composes, or conducts music.
Some cultures may or may not include the above aspects, or include their own aspects, in their definitions of music. For instance, in classical Indian music there is no conception of harmony or vertical relationships, and the Blackfoot do not consider bird "song" to be music. Some cultures would include dance.
Most cultures use at least part of the concept of preconceiving musical material, or composition, as held in western classical music. Many but fewer cultures also include the related concept of interpretation, performing material conceived by others, and less still the contrasting concept of improvisation, material which is spontaneously thought of while performed, not pre-conceived. However, many cultures and people do not have this distinction at all, using a broader concept which incorporates both without discrimination. Improvised music virtually always follows some rules or conventions and even "fully composed" includes some freely chosen material. See also, precompositional. Composition does not always mean the use of notation, or the known sole authorship of one individual.
Deaf people can experience music by feeling the vibrations in their body; the most famous example of a deaf musician is the composer Ludwig van Beethoven, who composed many famous works even after he had completely lost his hearing. In more modern times, Evelyn Glennie, who has been deaf since the age of twelve, is a highly acclaimed percussionist. Also, Chris Buck, a violinist virtuoso and New Zealander, has recently developed deafness. See: Baschet Brothers. See: psychoacoustics.
The music that composers make can be heard through several media; the most traditional way is to hear it live, in the presence, or as one of, the musicians. Live music can also be broadcast over the radio or television. Some musical styles focus on producing a sound for a performance, while others focus on producing a recording which mixes together sounds which were never played "live". Recording, even of styles which are essentially live often uses the ability to edit and splice to produce recordings which are considered "better" than the actual performance.
In many cultures there is less distinction between performing and listening to music, as virtually everyone is involved in some sort of musical activity, often communal. Sometime in the middle 20th century, listening to music through a recorded form, such as sound recording or watching a music video became more common than experiencing live performance. Sometimes, live performances incorporate prerecorded sounds; for example, a DJ uses records for scratching.
Many people also study about music in the field of musicology. The earliest definitions of musicology defined three sub-disciplines: systematic musicology, historical musicology, and comparative musicology. In contemporary scholarship, one is more likely to encounter a division of the discipline into music theory, music history, and ethnomusicology. Research in musicology has often been enriched by cross-disciplinary work, for example in the field of psychoacoustics. The study of music of non-western cultures, and the cultural study of music, is called ethnomusicology.
In Medieval times, the study of music was one of the Quadrivium of the seven Liberal Arts and considered vital to higher learning. Within the quantitative Quadrivium, music, or more accurately harmonics, was the study of rational proportions.
Genres of music are as often determined by tradition and presentation as by the actual music. While most classical music is acoustical in nature, and meant to be performed by individuals, many works include samples, tape, or are mechanical, and yet described as "classical". Some works, for example Gershwin's Rhapsody in Blue, are claimed by both Jazz and Classical Music.
As cultures of the world have been in more contact with each other, their indigenous music styles have often melded to form new styles. For example, the U.S.-American bluegrass style has elements from Anglo-Irish, Scottish, Irish, German and some African-American instrumental and vocal traditions, and can only have been a product of the 20th Century.
