What is the author's tone in Music Lessons by Mary Oliver?

"Music Lessons" is heavy with sibilants, the sound perhaps evolving out of the writing of the poem and then developed further to help keep the poem a unified whole. If there is another reason why whispering, buzzing, and hissing sibilants, say, instead of liquids, were employed it might be their connection to vibration, especially the vibration of the strings in the piano. Once in a while, the poem also employs assonance, as in "rock over rock to the top" or "neat green," which seem little more than pleasurable sound symmetries to keep one interested in reading.