The following paper is now available online at JASA Express Letters; full text is available at http://scitation.aip.org/journals/doc/JASMAN-ft/vol_125/iss_1/EL27_1-div0.ht..., or by emailing me (Marla.Holt@noaa.gov): Speaking up: Killer whales (Orcinus orca) increase their call amplitude in response to vessel noise Marla M. Holt, Dawn P. Noren, Val Veirs, Candice K. Emmons, and Scott Veirs Abstract: This study investigated the effects of anthropogenic sound exposure on the vocal behavior of free-ranging killer whales. Endangered Southern Resident killer whales inhabit areas including the urban coastal waters of Puget Sound near Seattle, WA, where anthropogenic sounds are ubiquitous, particularly those from motorized vessels. A calibrated recording system was used to measure killer whale call source levels and background noise levels (1-40 kHz). Results show that whales increased their call amplitude by 1 dB for every 1 dB increase in background noise levels. Furthermore, nearby vessel counts were positively correlated with these observed background noise levels. ©2009 Acoustical Society of America -- __________________________________ Marla M. Holt, Ph.D. NRC Postdoctoral Associate Marine Mammal Program NOAA/NMFS Northwest Fisheries Science Center 2725 Montlake Blvd East Seattle, WA 98112 Phone: 206.860.3261 Fax: 206.860.3400 www.nwfsc.noaa.gov/research/divisions/cbd/marine_mammal/marinemammal.cfm