Sound Science Archives

Whale Fins Inspire Quieter, More Efficient Fans and Wind Turbines - Humpback whales are the inspiration for a new approach to blade design being used in fans and tested for wind turbines. The bumps along the edge of the whales' long fins had long been considered an anatomical anomaly, but a biology professor in Pennsylvania has shown that they channel water across the surface of the fin in ways that create more maneuverability and power. Dr. Frank Fish has formed WhalePower to develop new industrial designs based on this discovery; the results are a sharp break from previous attempts to make fan and turbine blade edges as smooth as possible.

The first commercial result are factory fans up to 24 feet in diameter, which use 20 percent less energy and are significantly quieter than previous designs, while distributing the air more evenly. WhalePower is also developing wind turbine blades based on the new design; the first field trials are underway in Canada, and Fish says, "We can actually get more power out of the wind." Source: Christian Science Monitor, 5/16/08 [READ ARTICLE]

Eavesdropping on Noisy Fish - The National Marine Fisheries Service is turning to passive acoustics--ie, listening via hydrophones--in its efforts to identify key spawning grounds for fish species. By listening to the underwater soundscape, there are a lot of things we can determine about what’s out there and what they are doing,” said Brandon Southall, director of the ocean acoustics program at the National Oceanic and Atmospheric Administration. The agency hopes that passive acoustics can help identify breeding grounds in need of protection and can be used as a tool to assess population numbers accurately. Such noninvasive techniques would be a big step forward, Dr. Lobel of Boston University said. “Without passive acoustics, they have to catch endangered fish like cod and cut them open to see if they are ripe with eggs,” he said. “They have been killing tons of fish just to find out where they are spawning.” Increasing appreciation for the wide range of fish species that rely on sound has raised some concern about whether shipping noise could make it more difficult for fish to find each other at spawning time, or for predators to find food; “The Top ten species of fish in the diet of a dolphin make sounds,” according to Joseph J. Luczkovich, an associate professor of biology at East Carolina. Source: New York Times, 4/8/08 (article includes collection of fish sounds and a nice video report) [READ ARTICLE]

How Strong is a Hurricane? Just Listen - An MIT researcher has established the first concrete data supporting his idea that hurricane intensity could be tracked by listening to the sounds of wind and waves, rather than the far more expensive fly-throughs by aircraft. Nicholas Makris, associate professor of mechanical and ocean engineering and director of MIT's Laboratory for Undersea Remote Sensing, found data from a hydrophone that happened to be in the path of Hurricane Gert in 1999. "There was almost a perfect relationship between the power of the wind and the power of the wind-generated noise," he says. There was less than 5 percent error--about the same as the errors you get from aircraft measurements. Wilson suggests that a line of acoustic sensors could be dropped from a small plane into the ocean ahead of the storm's path, while conditions are still safe, and could then provide detailed information on the storm's strength to aid in planning and decision-making about possible evacuations. The total cost for such a deployment would be a small fraction of the cost of even a single flight into the storm. In addition, permanent lines of such sensors could be deployed offshore in storm-prone areas, such as the Sea of Bengal off India and Bangladesh. Source: MIT News Office, 4/9/08 [READ ARTICLE]

Controlled Exposure Study Examines Beaked Whale Responses to Noise - A multi-year research program based at a Navy facility in the Bahamas is using hydrophones installed on the seafloor, along with suction-attached tags that record the sound heard by tagged whales to learn more about how dive patterns are changed when whales hear mid-frequency sonar signals. The Woods Hole periodical Oceanus featured a detailed article on this work, including pictures. Oceanus, 1/15/07 [READ ARTICLE] See also AEI's lay summary of the cruise report from their first field season [GO THERE]

MMC-Run Marine Mammal Research Program Introduced in House - Congressman Neil Abercrombie (D-HI) has introduced the National Marine Mammal Research Program Act of 2008 (H.R.5106).  The bill will create a national marine mammal research program to be administered by the Marine Mammal Commission.  Implementation of this research program will greatly improve our understanding of marine mammals, especially the impact sound has on these animals.  The need for increased support for marine mammal research was identified by the National Research Council (NRC) and the U.S. Commission on Ocean Policy (USCOP). In their most recent report to Congress, the Marine Mammal Commission stated as their first recommendation: “Establish a coordinated national research program on the effects of anthropogenic sound on marine mammals and the marine environment.” Source: Consortium for Ocean Leadership press release, 1/28/08 [READ PRESS RELEASE]
[See AEI Special Report on MMC FACA Report to Congress]

Humans Far More Senstive to Fine Sound Differences Than Other Mammals - Researchers at the Hebrew University in Jerusalem have found that auditory neurons in humans are far more sensitive to fine sound frequencies than most non-human mammals, with the exception of bats. The researchers found that a single auditory neuron from humans is sensitive enough to distinguish very subtle frequency differences, down to a tenth of an octave. By comparison, a cat showed a sensitivity of about one octave, rats about a third of an octave on average, and the macaque about half to one octave. Such selectivity is not needed for speech comprehension, but it may have a role in musical skill. There is also evidence that frequency discrimination in humans correlates with various cognitive skills, including working memory and the capability to learn, but more research is needed to clarify this puzzle. Source: Daily Times, 1/14/08 [READ ARTICLE]

Quiet Autonomous Gliders Promise "New Era" in Acoustic Monitoring - A major step forward in acoustic monitoring has passed its first test. “We are entering a new era of underwater sensing,” says Jim Theriault of Defence Research and Development Canada, in Dartmouth, Nova Scotia, who ran the first trial of small torpedo-shaped "gliders" as a platform for acoustic monitoring. Unlike other systems, which require a boat nearby to monitor either the tagging of whales or other autonomous vehicles, the gliders can use a satellite phone connection to return data to distant research bases. Also, the new system has enough data capability to detect not only low-frequency baleen whale calls, but also the high-frequency calls of sperm and beaked whales, deep-diving species of special concern in sonar studies (there are some indications that sonar signals can disrupt their natural dive patterns, perhaps causing injuries due to surfacing too quickly or not having enough time at the surface between dives). Peter Liss from the University of East Anglia in Norwich, U.K., chairman of the U.K. government’s Inter-Agency Committee on Marine Science and Technology suggests that these gliders could be used in research to finally pin down whether noise does actually upset whales. “The link is probably there, but rather tentative,” he says. Since the glider is quiet and isn’t being followed at a close distance by a noisy ship, it should be able to gather the data needed to prove—or disprove—a link between sonar and whale strandings, he suggests. The glider being trialed runs on batteries and can last up to a month. But plans are afoot to make a low-power glider that can prowl the oceans for up to five years. Source: Conservation Biology, Oct-Dec 07 [READ ARTICLE]

First Human Fatality Due to Ocean Noise Reveals Whales Deafened by Ship Noise - After a passenger on a ferry in the Canary Islands died when the ferry struck a whale, biologist Michel André examined the ears of two whales killed in ferry collisions, and found tissue damage in both that indicates the whales were probably deaf. "The inner ear lesions we found in sperm whales came from two resident whales which died after collisions. These lesions affected animals of different ages," André says, indicating the damage is due to an external factor, not to ageing. The injuries also occurred at a place in the ear’s sensitive structure corresponding in frequency with the sounds emitted by shipping. To test whether the wider whale population was affected, his team ran controlled exposure experiments on 215 sperm whales in the Canaries in which they played sounds in the same low-frequency range as the affected regions of the ears. The whales failed to react. While it is impossible to be scientifically certain, André felt that the correspondence between the sound frequency emitted by shipping, the area of damage to the whales’ ears, and the lack of response by other whales to sound broadcast at the same frequency built a compelling argument: "It is very likely that these lesions are due to a long-term exposure to low-frequency sources," he concluded. André is developing a whale detection system that aims to hear whales and notify ships of their location in waters around the Canaries. Source: Powerboat World, 10/31/07 [READ ARTICLE]

D-tags Listen in on Manatees' Sound World - D-tags, which record the sound heard by an animal while tracking its motion in the water, have become a key tool in biologists' efforts to understand the effects of sound on cetaceans. Now, researchers have adapted D-tags for use with manatees (their non-invasive suction-cup attachment system had to be changed to work with rough-skinned manatees). Synchronizing boat sounds with the manatees' behaviors allows researchers to learn how manatees react -- or don't react, as filmed observations showed -- to boats. It will also allow researchers to determine if manatees react differently in shallow water versus deep water, where they might have more places to hide. This year, a total of 10 wild manatees were tagged. Florida State University researchers Doug Nowacek and Athena Rycyk said it is too early to draw conclusions about what they hear on the tags, although the sound files are interesting. “We hear a lot of chewing,” Nowacek said. Roars recorded from some passing boats was startling, Rycyk added. “When a boat flies by, especially a boat moving fast, it is really, really loud,” she said. What's more, boats can be heard for up to a minute before actually passing near the manatee. For years, Florida wildlife managers have asked boaters to slow down in areas populated by manatees. Reducing speed, they theorized, would give boaters a better chance of seeing and avoiding manatees on the surface and would give the animals fair warning to move away. But as the number of collisions has ballooned, critics have argued that manatees may not hear the motors of a slow-moving craft until the vessels are nearly on top of their backs. Recording sound will also help scientists learn about the sounds that manatees make: what type of vocalizations they use, how often they vocalize and how vocalizations change depending on their activity. Sources: Photonics, 10/16/07 [READ ARTICLE] WHOI Oceanus Magazine, 10/11/07 [READ ARTICLE]

Sounds of Bees Scare Elephants - African villagers trying to protect their crops from hungry elephants may have a new tool at their disposal: bees. Even recordings of bees could work, for a short while at least. While the animals rested, researchers played either buzzing sounds recorded at beehives, or a control sound of white noise. The buzzing clearly had the animals concerned. Ninety-four percent of the elephant families left the tree within 80 seconds of hearing bee sounds, nearly half of the time at a run. White noise, by contrast, only scared away 27% of the families. "So you could use sounds to deter elephants," noted Dr King, "but there are two major hiccups. Firstly, farmers don't have money to pay for a loudspeaker and a minidisc, and on that level it's not practical. Secondly, elephants are smart and would work out that there are no painful beestings; we don't know if that would happen after three playbacks or 30, but it is clearly going to happen." It might be more practical and more desirable, she believes, to use real bees rather than their sounds. Another of the projects that the group is running in Kenya involves creating a "beehive fence", where the passage of a hungry elephant would trigger bees to start flying and buzzing, giving the animal cause to turn and not come back. Source: BBC, 10/8/07 [READ ARTICLE]

Coronal Loops on Sun Carry Sound Like Pipe Organ - Immense coils of hot, electrified gas in the Sun's atmosphere behave like a musical instrument, scientists say. These "coronal loops" carry acoustic waves in much the same way that sound is carried through a pipe organ. Solar explosions called micro-flares generate sound booms which are then propagated along the coronal loops. "The effect is much like plucking a guitar string," Professor Robert von Fay-Siebenbuergen told BBC News at the National Astronomy Meeting in Preston. The coronal loops arch hundreds of thousands of kilometres above the Sun's surface like huge fiery fountains, and are generated by the Sun's magnetic field. Solar explosions called micro-flares send immensely powerful acoustic waves hurtling through the loops at tens of kilometres per second, creating cosmic "organ music". "These loops can be up to 100 million kilometres long and guide waves and oscillations in a similar way to a pipe organ," said Dr Youra Taroyan, from the Solar Physics and Space Plasma Research Centre (SP2RC) at the University of Sheffield. The sound booms decay in less than an hour and dissipate in the very hot solar corona. Source: BBC, 4/20/07 [READ ARTICLE]

Nerves May Use Sound, Rather Than Electricity - A new study by Danish scientists suggests that communication between nerves may take place via sound or vibratory waves, rather than electrical impulses, as long belived. The lack of evidence for heat given off by nerves, as would be expected if electricity were involved, led to the new inquiries. The researchers propose that the lipid fats in the membranes of nerve cells could transmit vibrations efficiently. Their suggested mechanism could also explain how anethesia works; changes in the temperature of the lipids would diminish their ability to transmit information between nerves. Source: CBC, 3/9/07 [READ ARTICLE] Press Release (with picture), 3/7/07 [READ PRESS RELEASE]

New Studies Reveal Blue Whales Regional Dialects, Behavior - Two studies at Scripps Institute of Oceanography have shed new light on the acoustic communication of blue whales. In one, researchers identified specific regional dialects that suggest the extent of sub-populations of the whales. Some populations, such as along the east coast of North America, are fairly concentrated in one area, while others, including one that ranges across much of the North Pacific, are more wide-spread. The paper suggests that the stock structures of blue whales, traditionally based on International Whaling Commission boundaries, should instead be reconstructed based on song, which would more accurately represent their true population distributions. A second new study has, for the first time, corelated the sex and behaviors that are associated with several well-known blue whale calls. "This is the first study that has been able to study the calls by directly observing the animal while it is calling and gathering key information such as depth and body orientation—getting a sense of what the animal is doing underwater," said researcher Erin Oleson. "Once you understand the context of specific types of sounds, then you can use those sounds to infer something about what they are doing when you are not there to actually see them doing it." Source: Scripps Press Release, 2/27/07 [READ PRESS RELEASE]

Listening System Could Protect Whales from Ship Strikes, Construction Noise - An inexpensive system of hydrophones developed by Chris Clark at Cornell is being tested for two new applications aimed at protecting critically endangered Atlantic right whales. Arrays of submersible bouys outfitted with recording gear are capable of recording up to 1400 hours of ocean sounds before returning to the surface for collection. Once back on shore, researchers will analyze the recordings to see whether the right whales vocalize enough to make the system useful as a whale-tracking network. Currently, aerial surveys attempt to notify ships of the presence of whales, but it is hoped that the acoustic system will be cheaper and better at spotting whales. NOAA is also considering using the "pop-ups", as they are nicknamed, as a monitoring system during construction of a LNG terminal off the coast of Massachusetts, to track any changes in whale acoustic behavior and to tell if whales are close enough to be injured by close exposure to high levels of noise. While some shipping companies are reluctant to slow down for right whales, others are embracing the new information. “It’s a pretty groundbreaking thing to actually have these companies in a situation where they might have to do monitoring and mitigation, where previously they’ve been able to do what they want,” she said. Hopefully this project will get underway before it’s too late — today only about 350 North Atlantic Right Whales exist, and every death is another huge step towards extinction. “Basically if we could prevent the death of two females per year that could cause their population decline to level out,” says Cornell researcher Ingrid Biedron, “So every ship strike could be the one that causes extinction, and every one that is prevented could be the one that causes the population to level out or even start increasing.” Sources: Cornell Daily Sun, 2/28/07 [READ ARTICLE] AP/Portland Press Herald, 2/10/07 [READ ARTICLE]

Study Confirms Birds' Changing Songs in Cities - Field studies in ten European cities, including London, Paris, and Prague, have confirmed that great tits adapt their songs to be better heard above a variety of noise conditions. The city-dwelling birds, a species that has adapted well to urban settings, were compared to forest-dwelling birds nearby. In songs important for mate attractions and territory defense, the urban songs were shorter and sung faster than the forest songs. The urban songs also showed an upshift in frequency that is consistent with the need to compete with low-frequency environmental noise, such as traffic noise. The capacity of great tits to sing within a relatively wide frequency range, and the ability to adjust songs by leaving out lower frequencies, seems critical to the bird's ability to thrive despite urban noise. Species without these capacities may have no other choice than to escape city life. An earlier study by the same researchers had identified frequency differences in great tit songs in one urban area, reflecting the amoung of low-frequency noise they had to be heard above; this study expands the findings to include many populations of tits, and compares urban to rural populations. Source: ScienceDaily, 12/5/06 [READ ARTICLE] [HEAR AND SEE AUDIO FILES OF URBAN AND RURAL SONGS]

Humpback Make Over 600 Distinct Sounds - A new study of humpback whales off the coast of Australia has identified 622 distinct sounds, which cluster into 35 basic call types. These sounds are typically short and discrete, unlike the long "songs" for which humpbacks are famous. "I wouldn't say (whales possess) language, as that's a human term. Whales don't string these sounds together like words and form sentences. It's more like a simple vocabulary," said researcher Rebecca Dunlop. She said these included "wops" made by females, "thwops" made by males, "yaps" made when pods split, and high pitched cries that appeared to express anger. Another new discovery was that whales also sometimes "speak" short song units individually instead of singing them, most commonly males trying to win the attention of a female in the midst of more than one whale singing. Source: Underwater Times, 11/20/06 [READ ARTICLE]

Beaked Whale Dive Patterns Studied - Ongoing study of dive patterns of beaked whales being carried out by a team at Woods Hole suggests that the possibility of decompression issues is more complex than first suspected. Earlier analysis of the dive patterns showed that the whales ascend more slowly than they descend, which led to some speculation that exposure to mid-frequency sonar might cause them to rise too quickly, causing injuries similar to "the bends." The new paper suggests that it is likely that the whales' lungs are fully collapsed at depths below 100m, so that the rapid ascent should not cause problems below that depth. Lead researcher Peter Tyack said, "We think that beaked whales return to the surface after deep dives with an oxygen debt and need to recover before their next deep dive." Tyack said the team's analysis suggests that the normal deep diving behavior of beaked whales does not pose a decompression risk. "Rather, it appears that their greatest risk of decompression sickness would stem from an atypical behavioral response involving repeated dives at depths between 30 and 80 meters (roughly 100 to 250 feet), " Tyack said. "The reason for this is that once the lungs have collapsed under pressure, gas does not diffuse from the lungs into the blood. Lung collapse is thought to occur shallower than 100 meters (330 feet), so deeper parts of the dive do not increase the risk of decompression problems. However, if beaked whales responded to sonars with repeated dives to near 50 meters (165 feet), this could pose a risk." Source: WHOI Press Release, 10/19/06 [READ PRESS RELEASE]

Kauai Crickets Develop Silent Wings to Avoid Parasite - On Kauai, male field crickets have quickly evolved female-like wings incapable of creating their characteristic chirping sound. In only 20 generations, 90 percent of male crickets have become silent, and so avoid predation by a parasitic fly that uses cricket song to find hosts. The flies deposit larvae in the crickets, which then are later killed when the flies emerge. The now-silent males have made behavioral adaptations to be able to attract mates: they congregate near the few remaining calling males and intercept females attracted by the calls. "While we were surprised by the extraordinary speed at which the mutation spread, what is more interesting is that, ordinarily, you would expect such a change in wing morphology to quickly disappear, because males couldn't attract mates," researcher Marlene Zuk said. "Instead, the behavior of the flatwings allows them to capitalize on the few callers that remain, and thus escape the fly and still reproduce. This is seeing evolution at work." The end of this evolutionary story is yet to be written: are the remaining singing males too rare to support the wasp population, or will they die off completely, and if so, will the silent males be able to find mates? Source: ScienceDaily, 9/26/06 [READ ARTICLE]

Two New Large-scale Acoustic Techniques Aim to Study Fisheries - High-frequency fish finding sonars are widely used to locate ocean fish, but they can only "see" a 10m-wide section of water at a time. A new system, Ocean Acoustic Waveguide Remote Sensing, uses low frequency signals to track large groups of fish over thousands of square kilometers, enabling researchers to watch as schools and shoals form, divide, and scatter. The system uses lower-powered signals than those emitted by naval submarine-seeking sonars. After initial tests in 2003, the system is due for further testing this fall in the Gulf of Maine. Another new system, the proposed Ocean Tracking Network, is being tested off the western coast of Canada. The network is centered on acoustic receivers deployed at sea, which listen for signals emited by acoustic tags surgically implanted in fish. The tags last from six months to two years; some simply note the presence of the fish, while others can collect more detailed data including daily locations, temperature, and depth, to better track long-term movement of individuals. Scientists hope to deploy such networks of receivers in 14 ocean regions throughout the world. Source: Science, 8/11/06 [READ ARTICLE]

Manatees May "Hear" Through Sensitive Hairs Covering Their Bodies - Intriuguing new research has revealed that manatees have highly sensitive hairs that are used much like whiskers, providing exquisite sense of touch. More intriguing, the neural system processing these sensations is linked to their auditory system. It is possible that manatees use these hairs to help them hear low frequency sounds, which their auditory system is not tuned to. Recent research has shown that manatee hearing is most sensitive to high frequencies, 16-18kHz, which has called into question protection measures based on making boats slow down (since manatees may, in fact, better hear the high whine of faster-moving boats). A new study found that manatees could detect sounds below 1kHz, and new research is underway to confirm whether the hairs are the source of this ability. Source: Collision Detection, 9/06 [READ ARTICLE] NY Times, 8/29/06 [READ ARTICLE]

Volcanic Activity Turned into Sound - Geologists have developed a new sonification technique that translates seismic activity data into sound. Listening to the sound files, as well as creating "scores" that can be analyzed, may allow scientists to detect subtle changes that precede increased activity. Source: ScienceDaily, 8/10/06 [READ ARTICLE] LISTEN TO SOUNDS: [MOUNT ETNA(aif)] [TUNGURAHUAS(aif)] SEE SCORE: [TUNGURAHUASA(pdf)]

Ultrasound Affects Embryonic Brain Development in Mice - Prolonged exposure to ultrasound caused small but significant changes in neural development in mice during late stages of embryonic development. The degree of the effect, in which neurons remained scattered rather than migrating to their proper locations, varied widely but increased as the duration of ultrasound exposure went up. Effects were seen with 30 minutes of exposure; researchers stressed that the use of ultrasound for medical diagnostics is not questioned by these results, but that the study should warn against non-medical use of ultrasound. Source: ScienceDaily, 8/9/06 [READ ARTICLE]