Answer:
The author's purpose in using sensory detail is to show that the narrator understands the value of the piano now that she is older.
Explanation:
The brief excerpt we are studying here was taken from a story called "Two Kinds" written by author Amy Tan. In the story, the narrator is June, the daughter of a Chinese woman in the US. Suyuan, the mother, has high expectations for her daughter. She wants her to be some sort of Shirley Temple, a child prodigy, so she forces June to take piano lessons. June defies her mother throughout the story and, finally, performs awfully at her piano recital to her mother's disappointment.
In the excerpt, June has had the piano tuned after her mother's death. The author uses sensory details - the touch on the keys, the rich sound - to show how differently June feels toward the piano now that she is older. The piano is no longer a nuisance, or even an enemy. It sounds beautiful because it no longer represents a forced destiny, someone else's wishes as to what June should be.