# BookLLM

Audible's technology team applies controllable text-to-speech to audiobooks: a large language model first builds a fixed voice profile for each character and writes natural-language stage directions such as "whispering nervously" for each line, and a speech model then synthesizes from them. Character attribution reached 97% and 94% accuracy on 25 English and Spanish mystery, sci-fi and romance books; in a MUSHRA listening test, dialogue differentiation improved by 3.7 points, and eight of ten voices showed statistically significant listening gains across English and Spanish tests.

Audible's technology team applies controllable text-to-speech to audiobooks: a large language model first builds a fixed voice profile for each character and writes natural-language stage directions such as "whispering nervously" for each line, and a speech model then synthesizes from them. Character attribution reached 97% and 94% accuracy on 25 English and Spanish mystery, sci-fi and romance books; in a MUSHRA listening test, dialogue differentiation improved by 3.7 points, and eight of ten voices showed statistically significant listening gains across English and Spanish tests.