A loner by nature, Knuckles is independent, headstrong and serious, yet gullible and short-tempered to a fault. He is entirely devoted to his duty, spending most of his time on Angel Island protecting the Master Emerald, and rarely cares for anything that is of no importance. When his friends and others are in need of his help, however, Knuckles can always be relied on being willing to leave his post and prove himself a faithful and good-hearted hero. He is also one of Sonic's oldest friends and rivals.

For vocal reference, use the Japanese voice of Knuckles, Nobutoshi Canna, as reference for your performance, which also experimenting with and trying out your own Slant and tones with the voice, any other references you use is completely up to you. We want to see your voice shine more than anything! 

For Vocal tone try going for that deep but rough sound to the voice, Knuckles is a serious yet short-tempered and mild mannered character so it's good to keep that in mind when auditioning and recording your lines.

Examples: https://www.youtube.com/watch?v=D8AZuAw7aCk