Your data will leak regardless because of typewriter keystroke acoustics [0]. So you better have a soundproof room for that purpose.

Keep any electronics out of the room that might have a microphone. Like phones, laptops, or running mechanical hard drives [1].

[0]: https://arxiv.org/abs/1609.09359

[1]: https://spqr.eecs.umich.edu/papers/Kwong-HDDphone-IEEE-SP-20...