Toothed Whale Hearing Senstivities Can Be Turned Up and Down
Supin, Nachtigall, Breese. Hearing sensitivity during target presence and absene while a whale echolocates. J. Acoust. Soc. Am. 123 (1), January 2008, 534-541
This very interesting paper, digging deeper into a topic that had emerged in previous studies of toothed whale hearing, reveals that a pilot whale could apparently “turn up” its hearing sensitivity, so that it could listen for fainter (more distant) sounds when echolocation clicks did not reveal nearby echoes. The research used a captive whale, outfitted with suction-mounted EEG electrodes to measure evoked potentials as it echolocated; half the time, a target fish was nearby, and half the time there was no nearby fish. When no fish was present, hearing sensitivity was 20dB higher (ie it could hear sounds 20dB more faint).

Aussie Humpback Calving Ground Threatened by Noise and Nets – A key humpback whale calving ground off the western Australia coast is targeted for at least three disruptive developments in the coming years, prompting calls for its designation as a World Heritage Site.Camden Sound, a natural harbour north of Broome, and adjacent bays and islands are the main calving grounds for humpback whales making a 13,000km return journey from Antarctica each winter.  Read the rest of this entry »

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]

Chukchi Lease Sale Set for February, Locals Seek Delay – The US Minerals Management Service has issued notice of its first oil and gas lease sale since 1991 along Alaska’s northwest coast. The sale, scheduled for February 6, covers about 25 million acres, out to about 200 miles offshore. The sale area will not include near-shore waters ranging from about 25 miles to 50 miles from the coastline, which includes the near-shore area through which bowhead and beluga whales, as well as other marine mammals and marine birds, migrate north in the spring, and in which local communities subsistence hunt. North Slope Borough Mayor Edward Itta said, “With all the changes happening out in the Chukchi Sea, I don’t think we should be adding to the problem with offshore oil exploration.”  Read the rest of this entry »

New San Diego Commuter Train Quieter Than Many Expected – The new Sprinter commuter train has begun test runs along lines that closely abut many residential areas in North County, CA, near San Diego. First impressions seem positive, with many residents noting the much quieter horns being used as the train approaches the many road crossings: the car-like horn sounds at just 85dB, as compared to standard freight and commuter train horns at 107dB. Tom Kelleher, a spokesman for the transit district, said he always expected the public to find the Sprinter much easier to live with than other passenger trains that traverse North County. “I think people really thought  Read the rest of this entry »