What is the act of performing a musical work in a different key called?

The act of performing a musical work in a different key is called transposition. This process involves shifting all the notes of a piece up or down to a new key while maintaining the same intervals between the notes. Transposition is often used to accommodate different voice ranges or instrument capabilities without altering the fundamental character of the music.

Transposition retains the original structure, melody, and harmonies, enabling musicians to adapt a piece for different performances or arrangements. It is particularly useful for performers who may need to play in a key that is more comfortable or suitable for their instrument or vocal range.

In contrast, modulation refers to changing keys within a piece, which typically involves moving from one key to another during the course of the performance rather than just starting the piece in a different key. Rearrangement involves altering the instrumentation, structure, or style of the work, while inflection refers to small alterations in pitch or rhythm within a specific performance but does not pertain to changing the overall key of the piece.