No, it will be distracting for you or another person, so it is better to sign without the voice to improve your signing skills. What about mouthing without the voice? Yes, there are many deaf people mouthing while signing but some do not use mouth for every word signs. For example, some words would use mouthing such as FINALLY which looks like PAH or LARGE which look like CHA! And it is not nice to stare at their lips if they are mouthing. Where you should look at is the eyes and body at the same time, just for your information.