I’m not sure what you mean. Do you mean hear yourself as others hear you? That’s a philosophical issue, not a practical issue. As others have pointed out, you can do recordings, but that leaves out some of the quality of the sound. But that’s only one side of the issue—the other side is how others hear. You can’t know that. You can never know what it’s like.
You can mess around with the acoustics of your own body all you want, but you’ll never know if you get an approximation of how you sound to others. I doubt you will. You’ll always have the connection between your vocal cords and your inner ear that you can’t get around.
So, in the end, you are left with a recording, no matter how poor that is, as the best way,
My advice is that you give up trying. Your recorded voice always sounds different to you when compared to your voice as you speak or sing. Do other people’s voices live and recorded sound the same to you? I think they sound closer to each other than my voice sounds to my recordings, but I don’t remember. I always sound weird in recordings—not how I sound to me.
Then again, the instrument I play sounds different in recordings than it does to me. But listening to other recordings, I find that the same instrument also sounds different from live in a similar way. So I’ve got to think that even the best recording leaves out a lot. Live is the only way to go. And you’ll never hear yourself as others hear you.