What is the definition of imitation in music?

Imitation in music refers to the technique where a musical phrase is initially presented by one voice or instrument and then restated or echoed by another voice or instrument. This creates a dialogical effect and can enhance the texture and richness of the musical composition. In this context, the phrase often involves the same melodic material being transposed or altered slightly, but fundamentally it retains its recognizable characteristics.

The other options do not accurately capture the concept of imitation. Repeating a phrase by the same instrument suggests a straightforward repetition rather than an interaction between different parts. A repeated phrase within the same voice lacks the essential element of contrast and dialogue between different instrumental lines that defines imitation. Lastly, a melody played in reverse pertains more to the technique known as retrograde rather than imitation, which focuses on the interplay of voices or instruments rather than mere reversal.