I believe finding your voice is paramount to achieving success in stand up comedy. Having great jokes is one thing but possessing the ability to drive them home in a spirited soulful way is HUGE for getting laughs. A stage voice can do that.
I believe your voice is in a few parts. It's part attitude, spirit, fun, drive and what you want or need to do. It's your overall story and philosophy and it should run through your material and performance like a river.
The thing to do is recognize it and then begin to harness the strength and vision of it.
To begin to find your voice it might be wise to record your stage work as much as possible. Then go over it and see if there are special moments within your act that are better than others. Ask yourself why? This could be the beginnings of your special way with humor. (voice)
Go over your material and be truthful as to what parts of it you REALLY love doing and what is so so.
Have someone you trust watch you and take notes. Sometimes it takes an objective person to see the spirit or attitude shift that drives the voice.
Listen when somebody says,
“I really love it when you do this or that”.
One way to find your voice is to look for it! Don't wait for it. Seek it out by getting to know yourself, and then apply it in your the writing of your material.