Logic to identify notes

[asdfgmxph]

Hi, I was wondering if you had any guidance towards post-processing Fourier Output

How did you derive the below formula utilized here?
Math.pow(10, 5 + wave[i] / 10)

I checked the blog, by the way, super helpful and easy to read blog.
and it said:
but we can improve data for analysis by using Math.pow function