Noise can be distracting, especially to a person trying to concentrate on a difficult task. Studying annoying noises helps architects design better building environments and policy makers choose effective noise regulations.
To better understand how short noise bursts affect humans' mental state, researchers from the University of Nebraska – Lincoln played quarter-second-long white noise clips to test subjects as they worked on arithmetic problems.
The researchers noticed a slight general trend toward lower performance when louder noises were played, and also identified sound level ranges that caused participants to report significant levels of annoyance. The researchers report their findings at the 164th meeting of the Acoustical Society of America (ASA), held Oct. 22 – 26 in Kansas City, Missouri.
The motivation for the research came from NASA's low-boom supersonic aircraft program. Sonic booms, generated when aircraft traveling faster than the speed of sound leave cones of compressed air in their wake, are loud and potentially unnerving. In 1964, when the Federal Aviation Administration starting flying supersonic jets regularly over Oklahoma City as part of a test called Operation Bongo, many citizens filed complaints and damage claims. NASA is now working on developing aircraft that create softer booms, but is it not clear at what volume regular booms, as might be created by commercial supersonic aircraft flying over land, would be acceptable.
Lily Wang, an architectural acoustician at the University of Nebraska – Lincoln, worked with her graduate student Christopher Ainley to design an experiment to test how noise bursts affect the performance and perceptions of test subjects. Previous studies had looked at loud noises of more than 80 decibels (dB), louder than an average vacuum cleaner, and found a clear effect on subjects' ability to solve arithmetic problems. Wang and her team reduced the volume to see if they could find a threshold value under which the noise would not significantly affect the participants. Twenty-seven test subjects were asked to memorize 6-digit numbers, and then, when shown a 4-digit number, the subjects had to subtract the second number from the first number in their heads and type the answer on a keyboard. Occasionally the researchers would play a quarter-second burst of noise while the second number appeared on the screen.
The researchers tested noise bursts in the range of approximately 50 – 80 dBA. The dBA unit indicates that the volume was measured with a filter used to approximate the human ear's response to sound. The noise levels were comparable to about the sound level on a suburban street corner at the low end, to vacuum-cleaner loud at the high end. While the test subjects solved a lower percentage of problems correctly when interrupted with a noise at the louder end of the spectrum, the difference was not enough to be statistically significant. However, there was a significant difference in the levels of annoyance that the participants reported when quizzed afterwards about their perceptions of the noise environment. "The test subjects sort of adjusted to the quieter booms, but the louder ones remained jolting," says Wang. "This suggests that the acceptable noise from sonic booms should not be higher than 70 dBA once it gets inside the house."
The researchers' lab did not have the necessary equipment to mimic the very low-frequency component of the noise produced by sonic booms, Wang notes, but the work helped to quantify the effect of the short duration characteristic of the booms. As a next step, the researchers hope to study perceptions of the rattling component of noise that is often associated with supersonic jets passing overhead.
###MORE INFORMATION ABOUT THE 164th ASA MEETING
Charles E. Blue | EurekAlert!
Smooth propagation of spin waves using gold
26.06.2017 | Toyohashi University of Technology
A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
26.06.2017 | Life Sciences
26.06.2017 | Physics and Astronomy
26.06.2017 | Information Technology