A technique that measures the time it takes a signal such as sound or light to travel through a material and return to a detector. By knowing the speed of sound or light in the medium, the distance to the target can be calculated. TOFA technique that measures the time it takes a signal such as sound or light to travel through a material and return to a detector. By knowing the speed of sound… is used in ultrasonic testingA non-destructive testing (NDT) method that uses high-frequency sound waves to detect and evaluate internal flaws, discontinuities, or material properties in va… to identify the thickness and location of defects.