What does blotto voice mean?

Answer 1

This looks like a punning reference to the phrase "sotto voce" ( below the voice), meaning "spoken in an undertone." Blotto is a slang word for falling-down drunk, so it might mean "speaking like a drunken sot."

Answer 2

A "blotto voice" typically refers to a slurred or incoherent way of speaking that is characteristic of someone who is very drunk or intoxicated. It signifies that the person's speech is affected by alcohol or drugs, making it difficult to understand or articulate words clearly.