Identify the sentence type. he never smiled, he never frowned, he never changed his voice from the gentle-flowing key to which he turned the initial sentence.

The sentence most likely used  parallelism.  parallelism is the use of the components in a sentence that are the same grammatically or similar in construction, sound or meaning. it is used as a literary device in may works. examples are "james ran into the garden, into the room and into our hearts.", "like father, like son.", and "easy come, easy go."

I’m going to guess #4 since that seems pretty logical.