Volume 4, Issue 2, April 2008
Index of content:
4(2008); http://dx.doi.org/10.1121/1.2961169View Description Hide Description
Infrasound (acoustic signals below the 20 Hz limit of human hearing) has been known since the eruption of Krakatoa in 1883. This event registered on barometers around the world. In 1909, barometers also registered a strong signal from the now‐famous Tunguska event. As illustrated by these two cataclysmic events, infrasound energy can travel reasonably unattenuated for thousands of kilometers through refractive ducts in the atmosphere. Recognizing the utility of this energy as a tool for the remote study of atmospheric sources, and as a probe of the atmosphere, infrasound was commonly used to monitor atmospheric nuclear tests starting in the 1940's. With the Limited Test‐Ban Treaty that eliminated atmospheric nuclear testing and with the advent of satellite technology, infrasound research had declined dramatically by the early 1970's. The recent Comprehensive Nuclear Test‐Ban Treaty (CTBT) that banned nuclear tests of all yields, in all environments, included the use of a worldwide network of infrasound receiving arrays. This has led to a re‐birth of infrasound as a technology for monitoring the Earth's atmosphere and shallow crust for nuclear tests as well as other natural phenomena.
4(2008); http://dx.doi.org/10.1121/1.2961166View Description Hide Description
From the sound that threatened “to deafen whales” with a low frequency hum throughout the world's oceans (Anderson, 1991) to present day military exercises using active sonar, controversy about the effects of sound on the marine environment has continued for over two decades. Marine animals use sound for communication, navigation, detection of predators and prey, and identification of their habitats. But the ocean is filled with many interfering sounds, some naturally occurring such as earthquakes and volcanic eruptions, and others resulting from human activity. The largest contributor to anthropogenic (human‐caused) sound in the ocean is commercial shipping, which accounts for over 90% of international commerce. But other contributors, such as active sonar and seismic air guns, have very high source levels even though they affect smaller defined areas. Active sonar is used not only by the world's navies to detect and track potentially hostile underwater intruders, but also by scientific researchers to study the ocean environment and the animals that live there. Likewise sound pulses created by arrays of seismic air guns are used for geophysical research to understand structures and processes beneath the seafloor as well as by oil and gas companies to locate and quantify reserves of hydrocarbon fuels. The challenge is to balance these activities so they do not impact the health and safety of creatures, large and small, that live in the sea.
Noise as an Indicator of Quality of Life: Advances in Measurement of Noise and Noise Effects on Humans and Animals in the Environment4(2008); http://dx.doi.org/10.1121/1.2961167View Description Hide Description
A jointly‐sponsored session on “Advances in Measurement of Noise and Noise Effects on Humans and Animals in the Environment” took place for the first time at the meeting of the Acoustical Society of America in New Orleans (November 2007). It was organized by Ann Bowles representing Animal Bioacoustics and Brigitte Schulte‐Fortkamp representing Noise. Recent studies on both humans and animals were presented in two half‐day sessions, followed by panel discussions on selecting efficient metrics with which to discuss notions of soundscape versus acoustic topology versus acoustic environment, and “meta‐acoustic” influences on response to noise. The outcome of the session is summarized in this article in “snap‐shot” form, with a short overview of the papers presented, proposed concepts, and main topics discussed during the panels. The corresponding abstracts can be found in the Journal of the Acoustical Society of America, Volume 122, Number 5, Part 2, November 2007, 154th Meeting: Acoustical Society of America, p. 9–11 and 33–35.