Archive for the ‘Fun’ Category

A new record

Putting a new spin on the long-playing vinyl record, an editor at Instructables has devised a new method for producing LP records using a rapid prototyping “3D printer”.  Working directly from a digital audio file, Amanda Ghassaei uses the waveform profile to create a 3D computer model of the familiar LP groove, which is then built up in physical form by a UV-cured resin printer.

Despite the cutting-edge 16-micron resolution of the printer, the end result is rather crude, with a frequency response and audio quality as yet far beneath a typical analog vinyl record.  The all-digital noise introduced by the discrete print (in time, aliasing, and in amplitude, quantization) is also harsh compared with the traditional “warm” analog distortion sought after by vinyl enthusiasts and audiophiles.  Even so, one could foresee a niche market for one-off, just-in-time pressing of records to keep alive long out-of-print material (or new material that might be in limited demand).  Even though this can be accomplished with .mp3 files or CD-R discs, sometimes there’s simply nothing like setting needle to vinyl!

[via Wired]

Things that go thump in the night…

Maybe you are familiar with images of the northern lights or perhaps have been lucky enough to see them yourself, but did you know that apparently they also make a sound?  According to, acoustic researchers at Alto University in Finland have identified a clapping sound associated with the aurora borealis that occurs 230 ft above the ground!  Just as is true with most mystery noises, they are brief and faint, require very careful listening as well as very low background noise in order to be heard.   There is an audio recording on here if you want to listen…

aurora borealis

[via, photo: shawn malone]

Frozen spring

One of the things one learns studying acoustics (and many other physics topics) is that the behavior of a complicated physical system can often be simplified into an analogy of masses and springs.  The gobs of air that surround us have elasticity and they have mass, and these are the properties that allow waves to travel through the air as sound.

Perhaps a more intuitive example of a spring-mass system can be found in any toy store: the classic Slinky.  The familiar coil toy can be used to demonstrate lots of different wave phenomena (longitudinal waves, transverse waves, standing waves), and when that gets boring, it is more commonly used to demonstrate walking down stairs.

We recently came across this high-speed video of the very interesting spring-mass behavior of an extended Slinky at rest, dropped from height, in which the bottom end of the Slinky seems frozen in mid-air.  There are excellent technical explanations of what is going on out there (and probably on a tricky physics midterm or two), but suffice it to say that it all goes back to the interplay between mass and elasticity as the Slinky simultaneously contracts and falls.

[Via, @jenvalentino]

What do fireworks sound like on 72nd Street?

Getting off the train at 72nd St, on the subway platform we heard a funny sound and wondered ‘what is that?’  Well, it turned out to be the sound of fireworks above for the kickoff of the NYC Marathon.  A cell phone microphone does not completely do this justice but you can hear the reflections of sound off of the building facades and the overall reverberation somewhat.

Underwater Musical Acoustics

Even beluga whales appreciate good acoustics!  There isn’t much else to say about this video other than it will likely make you smile…