Why is there only one voice for all book characters?

There are 85 leveled books in total which were carefully designed to teach a child to read. Having one voice for the narration was intentional when we created Ooka Island. The female voice, Auntie Kay, takes on the role of a teacher who is always asking questions as a child reads. She points out more subtle pieces of the story to build comprehension.

The man's voice, Zobot, is the narrator that reads the text with the child from the very beginning, as a child may not be able to read at this earliest level. To have different voices for the different characters distracts from reading the text and interacting with the teacher's voice. At this stage of early reading, more than two voices become more like a movie with a cast of characters.