What Does Critical frequency Mean?
Critical frequency is a step frequency between the low-frequency bandwidth and the high-frequency bandwidth.
When the critical frequency in the range of 10 to 1000 kHz, the dispersion and attenuation strongly affect sonic logging and reflection seismology. Waves that propagate vertically in a sequence of thin layers lose high frequencies by stratigraphic filtering.
Waves reflected from steep reflectors in a thinly layered medium are attenuated and dispersed by evanescent filtering.
Trenchlesspedia Explains Critical frequency
The physical interaction between solids and fluids which varies with frequencies is represented by the dispersion of seismic waves in a fluid-saturated porous solid. The vibration of the fluid is slow and the amplitude is large in a low-frequency band.
On the other hand, the vibration of the fluid is fast with a small amplitude in a high-frequency band. In between these two frequencies is a step frequency called the critical frequency. Experimental results show that the critical frequency depends on the density of porous fluids and on the scales of the pores.