Why do the voices all sound so similar? I'm not talking about accent, I'm talking about the pitch, timbre, and other qualities of the voice themselves. For instance, all the phrases I heard sounded like they were said by a medium-set 45 year old man. Nothing from kids, the elderly, or people with lower / higher-pitch voices. I assume this expected from the dataset for some reason, but am really curious about that reason. Did they just get many people with similar vocal qualities but wide ranges of accents?