Doctors now examine almost every pregnancy in the United States with ultrasound. Measuring the travel time of sound waves in the ocean can help monitor sea temperatures and global changes. Sound barriers along highways reduce noise levels in surrounding neighborhoods, effectively halving the loudness of vehicles. Noise barriers line approximately 1400 miles of U.S. Federal highways alone, with the number growing by 90 - 100 miles every year. Ultrasound techniques use high-pitched sound waves and their reflections to image the inside of the body, break up kidney stones, and stop internal bleeding.
Sound waves can create high-energy bubbles in liquids.
Intense heat and quick cooling of these bubbles speeds up chemical reactions for synthesizing pharmaceuticals. To obtain the best possible audio environment, new concert halls are designed with moveable canopies, curtains, and chambers that can be individually positioned to enhance the unique sound of each presentation. Sound waves can identify defects in airplanes, bridges, and pipelines. 1900s - Magnetostrictive and piezoelectric devices are used to produce ultrasound at controllable frequencies. Submarine detection becomes possible.