Simulated backscattered coefficients using various ROI sizes of (a) 5 spatial pulse lengths (SPL) axially by 1 beamwidth (BW) laterally, (b) 5 SPL axially by 2 BW laterally, (c) 10 SPL axially by 1 BW laterally, and (d) 10 SPL axially by 2 BW laterally. Circle, asterisk, square, and triangle denote results from the non-Welch method with rectangular window, conventional Welch method, the new method, and the theoretical backscatter coefficient (BSC), respectively.