Posts Tagged ‘noise’

those gosh darn mystery noises ….

Above Average via YouTube

The sound heard round and round the world

It doesn’t get much louder than an erupting volcano: the eruption of Krakatoa in 1883 registered a recorded sound pressure level of 172 decibels at a distance of 100 miles, not so much loud as completely debilitating. Nautilus Magazine examines the unique acoustics of the Krakatoa eruption, which spawned the most distantly audible sound in recorded history. Not only was the eruption audible over 3,000 miles away, the resulting pressure pulse was detectable for days as it circled and recircled the globe.

To get a sense of what that sort of pressure disturbance really means, try this recent video of a volcanic eruption in Papua New Guinea:

This sound is on fire

Many aspects of a firefighter’s work are not quite like the movies, and locating each other is one of them, according to a recent story from KUT News in Texas.  Visibility is poor or nonexistent in a real fire, so firefighters often have to rely on sound rather than vision.  A Personal Alert Safety System (PASS) is a device that emits a loud audible alarm if the wearer stops moving for more than a few seconds, allowing colleagues to come to the rescue.  Researchers at the University of Texas at Austin are working on ways to improve this system, which despite saving many lives doesn’t always work as well as it could.

For starters, an active fireground is a loud, noisy place, from things like sirens, power tools, engines, and the fire itself.  But beyond that, heat can do funny things to sound—hotter and colder parts of a room make sound travel faster or slower, and these changes in the speed of sound can actually bend sound waves that would otherwise travel in a straight line.  (Similar effects occur outdoors when the air temperature varies with height, such as being able to hear campers far away across a lake that cools the air.)  This heat refraction can wreak havoc with audibility and locating the source of a PASS beacon.  The current UT research will provide valuable insight into the sensory environment within a fire scene, and how compensation might be made for some of these acoustic challenges.

 

Did you hear that meteor?

This past weekend, the Perseid meteor shower reached its peak overnight between Sunday and Monday.  With a little patience and clear skies, the electromagnetic radiation in the visible spectrum that meteors release is easily seen.  But did you know that meteors also release very low frequency radio waves, below 30 kilohertz? According to livescience, going back hundreds if not thousands of years, people have claimed to hear sounds of meteors as they raced across the sky.  The very low frequency radio waves travel at the speed of light (not at the speed of sound) and arrive at the same time observers see a meteor passing overhead.  However, the radio waves need a transducer to could create a sound that is audible to people. This phenomenon is known as electrophonics, and in order to study it further, physicist Colin Keay created sounds in ordinary objects by exposing them to very low frequency radiation in a laboratory. Lightweight, membrane-like objects such as aluminum foil, foliage, thin wires, even dry frizzy hair produced sounds that were easily heard.

2012 Geminid Meteor Over Texas

Never having heard this before, we thought we would head out to Long Island to try and hear it for ourselves. We saw and heard a few things…First, there are quite a few sky-watchers in New York, which unfortunately meant that second, people noise and car stereos are louder than the sound from meteors.  Also, being by the beach, the sound of the ocean waves were also louder than the meteors.  Even if we couldn’t hear them this time, and although there were a few passing clouds, meteor showers still create a wondrous sight.  We will just have to make plans to go somewhere a bit quieter next time.

 

New York Noise

After over two years of work, we are glad to say that the final report for our project Wind Turbine-Related Noise in Western New York has been published.  Funded by the New York State Energy Research and Development Authority (NYSERDA) and the Electric Power Research Institute (EPRI), and co-produced with EPRI and Colden Corporation, the study presents a detailed and long-term look at noise levels and resident satisfaction near a modern, utility-scale wind power facility in Wyoming County, NY.

Wind Turbines

The findings of the study fill a gap in the available wind turbine noise research specific to New York State, and include a separate Syracuse University policy paper with specific and actionable advice for a non-technical public policy audience.  Both the Final Report (13-03) and the Policy Paper (13-03b) can be found at the NYSERDA R&D site, and we plan to present the project at the Wind Turbine Noise 2013 conference this August in Denver, Colorado.

Keep it quiet

The New York Times’ City Room Blog is putting together a presentation of New Yorkers’ favorite quiet oases, and they’re looking for suggestions.  Public places submitted to the blog’s interactive map will be considered for the piece later this spring.  Of course, your favorite quiet place may not stay that way once it’s discovered by eight million New Yorkers (and our 50 million annual tourists), so you may want to keep your favorite quiet place, well, quiet!