I'm fond of the sound of a diamond stylus coursing through a torturous valley of vinyl. I use to be around and got to know the applications of ultrasound in medical imaging. Using sound waves in the megahertz range to diagnose all manner of abnormalities within human bodies without causing potential damage to tissues from ionizing radiation as x-ray does.
The ideology of ultrasound imaging is thrilling because it uses high-frequency sound waves to view inside the body. Can you imagine being able to see the movement of the body's internal organs and blood flowing through the vessels?