Answer:
Thematic transformation is a musical technique in which a composer varies the leitmotif, or musical theme, of a piece by using permutation.
Step-by-step explanation:
Thematic transformation is a technique of variation, where material is repeated in an altered form, and the changes can involve melody, rhythm, harmony, counterpoint, timbre, orchestration or any combination of them. A basic theme is repeated through a musical work, but it undergoes constant transformations. One of its primary developers was Franz Liszt, an example of its use in a composition is in his "Piano Sonata in B minor". The first theme is a descending scale marked sotto voce, leading to a jagged, forceful motif in octaves, followed by a hammering marcato motif, the followed by a dialogue until reaching the noble Grandioso material in D major. Then he transforms the marcato motif into a lyrical melody. The final recapitulatory section begins with a driving fugato which leads to the return of the opening material.