This is a book about music.

Music is an art form and cultural activity, and its medium is sound waves (a kind of mechanical waves) which are organized regularly. Its basic elements include strength, tonality, duration and timbre. These basic elements are combined with each other to form the common "formal elements" of music, such as rhythm, melody, harmony, strength, speed, mode, form and texture.

the formal elements that constitute music are the means of expression of music. Different types of music may emphasize or ignore some elements. Music is played by various musical instruments and vocal techniques, which can be divided into instrumental music, vocal music (such as songs without musical instruments) and works that combine singing and musical instruments.

in the most general form, music is described as an art form or cultural activity, including the creation, performance, evaluation of music, research on music history and music teaching of music works. Ancient Greek and Indian philosophers defined music as tones arranged horizontally as melody and vertically as harmony.

common sayings such as "harmony in all fields" and "this is music in my ear" point out the idea that music is usually orderly and pleasant to listen to. But John Cage, a composer in the 2th century, thought that any sound could be music. For example, he said, "There is no noise, only sound."

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