Kathy, it is true that "amenity" means "the quality of being pleasant or agreeable" (http://www.merriam-webster.com/dictionary/amenity), and the Oxford English Dictionary supports this; however, the word is usually used in reference to places ("places, their situation, aspect, climate, etc.") or people ("of persons, their habits, actions, etc.")

For example: " the attractiveness and value of real estate or of a residential structure; a feature conducive to such attractiveness and value." In plural: "something (as a conventional social gesture) that conduces to smoothness or pleasantness of social relationships ; something that conduces to comfort, convenience, or enjoyment ."

The OED says:

"In modern use, frequently in plural, "amenity" is applied to the more ‘human’ and pleasurable environmental aspects of a house, factory, town. . . . Also used concretely (usually in singular), a particular advantageous or convenient feature of this kind."

The use of "amenity" that you propose is not easily or immediately understandable though it might work in the context of a scholarly thesis, if the term is carefully defined and used consistently.

But you might do better to use more common or familiar terms, such as "pleasant sound," "pleasing sound" or "pleasing quality of sound," "agreeable quality of a sound," or the like.