Throughout the spring, some Bay Area residents from Marin County to the Presidio noticed a sustained, unplaceable high-pitched tone. In early June, the sound reached a new peak volume, and recordings of the eerie noise spread across Twitter and Facebook. Soon after, The Golden Gate Bridge, Highway, & Transportation District, the agency responsible for the iconic suspension bridge’s maintenance, solved the mystery: The sound was due to high winds blowing through the slats of the bridge’s newly-installed sidewalk railing. Though a more specific explanation was not provided, the sound is most likely an Aeolian tone, a noise produced when wind blows over a sharp edge, resulting in tiny harmonic vortices in the air.
The modification of the Golden Gate Bridge railing is the most recent and most audible element of a multi-phase retrofit that has been underway since 1997. Following the magnitude 6.9 Loma Prieta Earthquake in 1989, The Golden Gate Bridge, Highway, & Transportation District (The District) began to prepare the iconic bridge for the wind and earthquake loads that it may encounter in its hopefully long life. Though the bridge had already withstood the beating of the Bay’s strong easterly winds and had been rattled by minor earthquakes, new analysis technology and construction methods could help the span hold strong against any future lateral loading. The first and second phases of the retrofit targeted the Marin Viaduct (the bridge’s north approach) and the Fort Point Arch respectively. The third and current phase addresses the main span.
Continue reading “Bridge Over Trebled Water: How The Golden Gate Bridge Started To Sing”
A biographer of Frank Sinatra once commented that for singers like Sinatra, their instrument is the microphone. We tend to think of microphones as ideal transducers, picking up sound faithfully. But like most electronic components, microphones are imperfect. They have a varying frequency response. They pick up popping noises when we say words like “popcorn” that are normally lost to someone listening live.
[Cheddar] has an interesting video (see below) that covers how performers like Sinatra, Bing Crosby, and Billie Holiday learned to use the microphone to their advantage. They suggest that the microphone changed the way humans sing, and they are right.
Continue reading “Love Songs To The Microphone”
[Greg] was looking for something to build using his recently acquired Arduino, and with Halloween approaching, he thought a cool light display would make a great project. He browsed around online and found this tutorial that shows how to build a chorus of singing pumpkins controlled by a computer’s parallel port. Since he didn’t have any computers with a parallel port kicking around anymore, he decided to try his hand at recreating it with an Arduino.
[Greg] gathered eight light up Jack-o-Lanterns, along with a handful of relays and other miscellaneous components. He wired up the relays to trigger each individual pumpkin’s built in light when switched by the Arduino. He sat down and carefully listened through “This is Halloween” from The Nightmare Before Christmas, choreographing each of the pumpkins to take on the voice of one of the movie’s characters.
When the show begins, the display transforms from a group of unassuming pumpkins with candles a-flicker to a chorus of ghouls extolling the virtues of Halloween.
It really is fun to watch, so be sure to check out the video below. If you’re looking to throw together a quick display before the big day rolls around, [Greg’s] source code and diagrams should get you headed in the right direction.
Continue reading “Halloween Hacks: A Light And Music Show Fit For [Jack Skellington]”