Posts Tagged ‘noise’

Catch a wave

You may know that the sounds you hear travel through the air as waves, but the invisibility of air makes this concept a tricky one to visualize.  For those who like physics demonstrations (and who doesn’t), we recently came across this video of a series of pendulums—and the pendulum is perhaps the most accessible form of wave motion we witness in everyday life.

A pendulum’s length determines its frequency, just as sound waves in air have a frequency that corresponds to pitch.  The demonstration superimposes different frequencies to illustrate traveling waves, standing waves, beats, and “random” noise, which are all phenomena that come from mixing different frequencies together.

compostable quiet

Maybe you heard about this maybe you didn’t…or maybe you heard someone next to you eating SunChips out of the old compostable but VERY NOISY bag last summer. Well, Frito Lay just recently reduced the noise that the compostable bags make.  They found that by using a more rubbery adhesive to put the bag together, the noise level dropped from around 80 to 85 decibels to around 70 decibels.  Subjectively, a 10 decibel drop is about half as loud.  So maybe now you can sneak a snack at midnight without waking up your neighbors and then bury the evidence in your compost pile.  Happy Earth Day!

AP Article

Putting the rev back in your engine

A great deal of engineering effort has gone into quieting the automobile over the past century.  In most major cities, transportation noise is a huge contributor to environmental noise both outdoors and in (who doesn’t live near a road?)  Vehicle acoustics is a primary focus of many current applied acoustics research programs, with the enthusiastic support of the auto industry.

Even so, some would argue that these great successes in reducing vehicle noise have come at the expense of exhilaration; gunning your engine at a stop light just doesn’t give the thrill that it did in the days of the big block V8.

SoundRacer in actionFor those of us that would occasionally like to hear what we’re driving (which yes, sometimes includes even noise-averse acousticians), a Swedish company has developed the SoundRacer.  This gizmo fits into your cigarette lighter socket, and using the socket voltage to sense engine RPM, broadcasts real-time sports car engine sound through your car stereo.  Even if your “sports car” happens to be less than sporting!

Signal to Noise

Those of us in the acoustics world often talk about signal to noise ratio.  Wouldn’t it be more fun if it was a party instead of a ratio?  The Museum of the Moving Image is hosting its first Signal to Noise party this weekend as part of its grand re-opening out in Astoria.  The museum will be taken over with live electronic music, moving image performances, and interactive art.  Maybe we will see you there…

Signal to Noise

meet elvin…he’s an electric vehicle with interactive noise

(Although we haven’t checked under his hood, we think elvin is a boy)

At one time or another, you have probably been crossing the street or walking through a parking lot and out of nowhere comes a car.  What’s different is that it didn’t come roaring at you but rather it snuck up on you, sidled right on up next to you without you noticing.  Then you realize it’s a hybrid or maybe even a fully electric Mini E or a Tesla (not likely but possible).  This is where elvin comes in…

Engineers at the University of Warwick created elvin to experiment with sounds for electric vehicles.  On the one hand, since hybrid/electric cars are quiet at low speeds, as they become more popular there could be a significant reduction in environmental traffic noise levels.  On the other hand, sound from vehicles can alert pedestrians or cyclists of oncoming traffic.  Also, the sound a particular car makes or doesn’t make also adds to the branding and buyer’s perception of a vehicle.

elvin would like your opinion on how he sounds and has an online interactive evaluation.  Check him out.

elvin electric vehicle with interactive noise

Ch-Ch-Ch-Chia Wall???

Chia HeadProbably at one time or another you had a Chia Pet or at least knew someone who did.  How about the Chia Car?  Well, the Ohio Department of Transportation has come up with an environmentally friendly, aesthetically pleasing sound barrier, the Chia Wall if you will.  The naturally “green” noise barrier will separate a residential neighborhood from a noisy next-door interstate and will be constructed of bags of soil and seeds – just add water.