In the audio options there are be separate volume adjustments for effects, music and speech, but I don't know if there is a way to disable just the character's comments. I played a female character in Divinity 2 because I didn't care for any of the male voices (or most of the female ones; IMO the female soldier voice is ok). Your character doesn't make a lot of comments, though, so if you can find an acceptable voice, after the beginning of the game (with faster levelling and more equipment upgrades, etc) the frequency of comments goes down a bit.
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