Believe it or not, it is common for people who live far from railroad tracks to hear trains at night and only at night. While this may be due to trains only running in the evening or due to lower overall sound levels in the nighttime, there is a surprising physical explanation why a person might hear a train in the nighttime and not in the day.
Sound waves, like other types of waves, experience bending or refraction when ...
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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 ...
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In the previous post, we learned that the decibels belongs to a group of units called a relative units. This means that decibels are always expressed as a ratio of a measured value to a known reference value. There is, of course, a bit more to decibels than dividing one number by another, but don’t worry—the math isn’t too bad. We’ll walk you through it nice and slow.
So, why bother with more math in the first place? Shouldn’t it ...
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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 ...
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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 ...
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Let’s say you are preparing to go camping and mountain climbing. When you look through your supplies, you find ropes of many sizes. Two of them are tied in knots. You think that combined the two knotted ropes might be long enough for your plan, but you aren’t sure. So what do you do?
Easy: you untangle the ropes so you can measure them.
Adding decibels works the same way—they need to be untied before you can use them to go adding ...
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When most people hear the word acoustics they think of acoustic guitars or concert halls, but the field of acoustics is actually much larger than internet covers of radio songs and plush theatre seating. The word acoustics comes from a Greek word akoustikos which means “of or for hearing”. The contemporary definition of acoustics is broader than the original Greek. Today, acoustics is the science of sound and vibration, which includes topics like noise control, ear health, SONAR, speech, structural ...
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