My mother's voice was like a cool, dark room in summer peaceful, soothing, quiet
identify the type of figurative language used in the excerpt and how it adds to the overall characterization,

Simile

Explanation:

The definition of a simile is a figure of speech involving the comparison of one thing with another thing of a different kind, used to make a description more emphatic or vivid. The fact the author included the phrase "like" means it is a simile rather than a metaphor, and ultimately the language used enhances the characterization of the mother in such a manner that she comes across as a calming, stabilizing character  

the rhyme scheme is abab cdcd efef gg.