Why in the Impact-echo technique, factor of 0.96 is present in the equation: f =(0.96*Cp)/(2*T) where f is frequency, Cp is velocity and T is depth ?

In 1997, Dr. Sansalone in her book "Impact-echo: nondestructive evaluation of concrete and masonry" says that this factor is 0.96 due several studies, but they not mention the reason for it.

28 December 2015 7,183 4 View