Posts Tagged ‘noise’

Restaurants have a sound opportunity

We are often asked to help find ways to improve acoustics and reduce crowd noise in restaurants, but when it comes to implementing them the disruption can be hard for an operator to accommodate. Even simple changes to ceiling finishes can mean a day or more of lost dining room revenue, in a business already on thin margins typical for NYC and other expensive places.

During COVID, we noticed that the restaurants that were fortunate enough to be breaking even with delivery and outdoor dining found themselves with once-busy dining rooms that were largely going unused. It’s a perfect opportunity to make what might have otherwise been disruptive changes to an interior, in anticipation of packed crowds returning once again. Carefully analyzed and thoughtfully implemented, good restaurant acoustics can allow diners to converse in a lively environment, without subjecting them to either an ear-splitting racket or an overly-deadened hush.

Acoustics center stage

As acoustical consultants, we’re often forced to work around extraneous noise. Especially in New York, trying to measure something that is quiet can be frustrating when it’s surrounded by things that are loud. While this tends to be unavoidable here, the New York Times features this piece on an acoustic task that was too important for interference: the digital cataloging of a Stradivarius collection in Cremona, Italy.

By building a model of samples and tones from each instrument, the project hopes to preserve their sound indefinitely even after the instruments degrade. But because the sounds are too subtle to withstand any extraneous noise, city activity and traffic around the Museo del Violino is completely suspended during recording, an unprecedented precaution only possible since the Stradivarius is the signature sound of Cremona. That level of control would be nice for our own work, but city noise is the signature sound of New York!

Sonic thump

NASA has awarded the contract to build its first piloted X-Plane in decades, with the mission to advance supersonic flight over populated areas. While the historic Concorde broke the sound barrier over the ocean, it was restricted to subsonic speeds over land due to the disruptive and objectionable sonic boom produced by supersonic flight. In the new Low Boom Flight Demonstrator design, the contours of the airframe and management of the flight profile will help to minimize and distribute the shocks over a wide area, producing a series of muffled thumps instead of the two sudden, loud cracks that occur when the leading and trailing sonic shocks coalesce in existing designs.

The research program is also advancing the analysis and prediction of supersonic noise propagation through the atmosphere, and how those of us on the ground perceive the new muffled signature—since public acceptance is the ultimate hurdle to commercialization.  New York to LA in two hours never sounded so good!

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.