What should I use for displacement distance for Vibration Calculation?

[CNBA3]

To simplify, this is to find calculate values for beats that require vibration. I already know the frequency for which to use in the calculation, I’m just wondering, what would the displacement be for distance?

For this kind of, I’m using the shaking visuals like human vision or camera as a reference. Should I use the displacement of how the eyes look up and down or the shaking of a human head?

Here is the link to the calc.

Thank you.

Vibration Measurement Calculator