What is defined as an instrument in the context of music?

In the context of music, an instrument is specifically defined as a device that produces musical sounds. This encompasses a wide range of tools, including traditional instruments like pianos, guitars, and violins, as well as electronic devices like synthesizers. The primary function of an instrument is to create sound through various means, whether that be through string vibration, air movement, or electronic signal generation.

Understanding this definition is crucial for recognizing the role of instruments in a musical composition or performance. The other options presented address different aspects of music but do not fit the definition of an instrument. For instance, a method of composing music refers to the processes involved in creating a piece, a notation system for music pertains to how music is written and read, and a technique for sound mixing relates to combining various audio elements in a recording. Each of these aspects plays an important role in music but does not align with the specific definition of what an instrument is.