All this information and understanding of sound, acoustics, and wave phenonema is actually very important in many situations. For example, musicians benefit from a better understanding when they play their instruments or perform in concert halls, architects and engineers need to know the science of sound better to design buildings like auditoriums and theatres, and even those in the field of medicine and medical physics will benefit from such knowledge.
For example, the idea of waves and frequencies is important in magnetic resonance imaging (MRI), which makes use of radio frequencies (~1 MHz - ~300 MHz) and magnetic fields to recreate images of the inside of the human body. Medical ultrasound uses sound waves with frequencies far above the range of human hearing (which is between ~20 Hz and 20,000 Hz) to create images of the body as well. Ultrasound is especially good to use when trying to detect distances. Ultrasound is also used in non-destructive testing (NDT), which does not damage the object being tested, hence the name. For example, if we had a block of metal and we wanted to know if the inside was damaged in any way, we might use NDT. High frequency waves would be fired at the object. We know the external size of the object and thus know how long it takes for the signal we sent to be reflected back to us. If the signal hits a defect or crack, then a reflected signal returns to us early, and we then know that there is an issue. To learn more about NDT, check this website out.
Knowledge of waves is important to those that work with Radio Detection and Ranging (RADAR), which is a method of detecting objects with sound waves, and Sound Navigation and Ranging (SONAR), which is a method of using sound to observe and communicate with objects on or under water, similar to RADAR. This is important in many branches of science, such as oceanography and underwater acoustics. RADAR and SONAR are also important tools for those that use planes and ships to travel (such as airlines and navies).
The study of sound even has applications in areas related to psychology. Studying how speech plays an important role in our world and how we process speech and sounds in the brain is an important field of study.
These represent just a few topics where sound and acoustics play a tremendous role. Fields that were discussed at a recent Acoustical Society of America include but are not limited to:
Another important area is that of noise-cancelling and minimization. We can actually describe sound as signals that are wanted and then noise refers to signals that are unwanted, deemed irritating or disruptive. In terms of the physics, desired signals and noise are the same, as both are created in the same way; what is different is our perception of different sounds. Think of when you are on board an airplane. You might have your headphones on, trying to listen to your music. Your music is the signal that you want to hear, but the airplane's engine hum is not wanted and can be considered noise. Or perhaps you really wish you could ignore that bawling baby or the stewardess arguing with the gentleman that refuses to put up his tray table.
Noise cancellation, or active noise control, is a way of minimizing or eliminating unwanted sounds (noise). The method uses the principles of interference and superposition that was discussed by adding a second sound wave to the desired signal that is specially created to cancel the first. Recall how destructive interference works.
Learn more about noise cancellation on the next page, where you can learn to build a circuit that reduces noise!