where is the frequency, and are the seismic wave amplitude spectrum after propagating traveltime and , respectively, is the initial amplitude spectrum, and is a factor independent of frequency. Combining equations 1 and 2, we can obtain:
(3)
Take a natural log of each side of equation 3, we obtain:
(4)
where and are both constants, and
,
. Here, can be estimated by the slope of linear regression line. Then, can be estimated by