How are multiple reflections of sound helpful to doctors and engineers?

Explanation

1) Doctors use multiple reflctions of sound to hear the sounds produced with in the body using stethoscope.
2) Doctors can see the images of patient's organs like liver, gall bladder, uterus etc. to know the abnormalities in their functioning using ultrasounds.
3) Engineers use the reflections of sound in designing concert halls and cinema halls.
4) Generally the ceilings of concert halls, conference halls, cinema halls are designed such that sound after reflection reaches all corners of the hall as shown in the figure.