What does "register" mean here?
Native speaker’s answer
Rebecca
"Register" here refers to the "vocal" register, meaning the range of tones of a human voice. In this video, the speaker has used "lower register" to express that his character's voice is naturally lower ("talks with a lower register"). Ex: When I get excited, my voice rises a register. Ex: I speak in a lower register naturally. For this reason, I sometimes sound monotonous.