High-frequency ultrasound has become a popular tool in characterizing small-scale soft materials. This method is particularly effective in pitch-catch mode. It has been used in tissue phantoms to evaluate the microstructure. This method has the potential to be used in determining the tissue pathology in cancer and other tissue degenerative diseases. Among different types of parameters of ultrasound, peak density has been found to be most sensitive to the microstructural and scatterer variations in soft materials. 25 MHz ultrasound wave is used in a pitch-catch mode to evaluate mm scale tissue phantoms with microscale scatterers on different thickness levels. FFT is used to convert the receiving signal to frequency domain, calibrate to remove the noise and analyze the peak density. Finite element simulation is used to model the wave propagation in the medium containing scatterers to find a systematic correlation with the scatterer density.