Posted by:
One of the first acoustics topics most physics classes cover is resonance. Often, physics teachers will show the video clip below of the collapse of the Tacoma Narrows Bridge (also known affectionately as “Gallopin’ Gertie”) to demonstrate the potential effects of resonance.
While the rippling motion of the bridge seems unreal, the physical principle of resonance is quite real. Gaining an ...
Continue Reading →Posted by:
The megaphone is one of the oldest acoustical devices. People learned early that horn-shaped or cone-shaped tubes could be used to increase the audibility of the human voice. However, it took much longer for humanity to discover exactly how megaphones amplify sound.
Many early civilizations used “speaking horns.” Some Native American leaders used birch bark horns to communicate with large groups. In ancient Greece, actors wore masks with cone-like openings around the mouth which amplified their voices. Many inventors ...
Continue Reading →Posted by:
When most people hear the word wave, they immediately think of ocean waves. While there’s nothing wrong about thinking about a sunny day at the beach, in terms of acoustics, the kind of waves you see crashing on the sand are not like most sound waves. In fact, crashing ocean waves are like the complicated nonlinear waves you find in a sonic boom situation.
Sonic booms may be cool, but if you want to understand sound waves, it’s best to start ...
Continue Reading →
The word decibel, abbreviated dB, seems to show up everywhere in acoustics: sound pressure levels, sound power levels, intensity levels, and even voltage levels. With so many usages, it is no surprise that a cloud of confusion lurks around the term. How could one unit describe so many different things? Shouldn’t different quantities have different units?
Well, the firstly it’s important to understand that the decibel is not an absolute unit like seconds or meters—it’s a relative unit. Absolute units can ...
Continue Reading →Posted by:
You’ve probably heard people talk about white noise to describe a rushing, static-like sound. The term white noise seems like a paradox. How can a sound have a color? Isn’t sound invisible?
Yes, you are absolutely correct—sound waves traveling through air are just as invisible to the naked eye as are the air particles themselves. (In order to “see” sound, you would need to be able to see the locations and movement of the air particles.)
The origin of the term goes ...
Continue Reading →