Acoustics's the interdisciplinary science that deals with the study of sound, ultrasound and infrasound (all mechanical waves in gases, liquids, and solids). A scientist who works in the field of acoustics's an acoustician. The application of acoustics in technology's called acoustical engineering. There's often much overlap and interaction between the interests of acousticians and acoustical engineers. Hearing's one of the most crucial means of survival in the animal world, and speech's one of… (More on Acoustics)