What might a composer use in real-time creation during a performance?

A composer often utilizes improvisation during a live performance to create music in real-time. This technique allows for spontaneity, where the composer can respond to the audience, the environment, or other performers, making each performance unique. Improvisation can involve altering melodies, harmonies, or rhythms based on inspiration or emotional response at that moment, which engages the audience in a dynamic way.

Other terms listed, such as notation, refer to written music that guides a composer on what to perform rather than allowing for immediate, creative input. Playback is typically the process of executing pre-recorded music, lacking the real-time creativity that improvisation provides. Sound design involves creating and manipulating sounds but doesn't necessarily require the on-the-spot creativity characteristic of improvisation in a performance. Thus, improvisation stands out as the most fitting choice for real-time composition during a performance.