Featured Research

from universities, journals, and other organizations

Built-in ear plugs: Whales may turn down their hearing sensitivity when warned of an impending loud noise

Date:
May 8, 2012
Source:
Acoustical Society of America (ASA)
Summary:
Toothed whales navigate through sometimes dark and murky waters by emitting clicks and then interpreting the pattern of sound that bounces back. The animals’ hearing can pick up faint echoes, but that sensitivity can be a liability around loud noises. Now researchers have discovered that whales may protect their ears by lowering their hearing sensitivity when warned of an imminent loud sound.

Toothed whales navigate through sometimes dark and murky waters by emitting clicks and then interpreting the pattern of sound that bounces back. The animals' hearing can pick up faint echoes, but that sensitivity can be a liability around loud noises. Now researchers have discovered that whales may protect their ears by lowering their hearing sensitivity when warned of an imminent loud sound.

The scientists will present the finding at the Acoustics 2012 meeting in Hong Kong, May 13-18, a joint meeting of the Acoustical Society of America (ASA), Acoustical Society of China, Western Pacific Acoustics Conference, and the Hong Kong Institute of Acoustics.

"Whale hearing may be the most fascinating marine mammal sense," says Paul Nachtigall, a biologist at the University of Hawaii who started his career studying otter vision, but soon switched to whale and dolphin echolocation. Earlier experiments by Nachtigall and his colleagues suggested that whales can actively shield their hearing from loud outgoing echolocation clicks, which can reach sound levels equivalent to a rifle fired right next to the ear. The scientists wondered if the animals could similarly protect their ears from incoming loud noises.

The team repeatedly played a short warning sound followed by a loud sound to a false killer whale working in the laboratory in a floating facility off Coconut Island at the Hawaii Institute of Marine Biology. They measured the animal's hearing sensitivity by placing suction-cup sensors on the skin of the whale's head and recording the frequency of its brainwaves. Initial results indicate that the whale significantly reduces its hearing sensitivity when warned that a very loud noise is about to arrive.

"It appears as though the whales learn this pairing of warning signal and loud sound rapidly through classical conditioning," says Nachtigall. Many human activities such as oil exploration and the use of ships' sonar create loud noises in the ocean. If wild whales could quickly learn the meaning of a short warning sound, the technique might help lessen the impact of anthropogenic noise on marine mammals, Nachtigall notes.

Whales' auditory systems are similar to other mammals' in structure, but larger in size, most likely because they have evolved for the special task of echolocation. Right now scientists aren't certain how the whales are able to adjust their hearing sensitivity. Bats, which also use sound to navigate, automatically contract muscles in their ears to reduce hearing sensitivity while they produce loud outgoing echolocation calls. Nachtigall says that whales may do something similar, but that understanding the mechanism will take considerably more work. "We think -- based on much of our echolocation work -- that it is much more than a simple reflex," he says.

So far, the team has only tested the warning signals with one false killer whale. In the future they would like to test additional species of marine mammals. "We are also very interested in how long it takes a naïve animal to learn to lower its sensitivity when warned," Nachtigall says.


Story Source:

The above story is based on materials provided by Acoustical Society of America (ASA). Note: Materials may be edited for content and length.


Cite This Page:

Acoustical Society of America (ASA). "Built-in ear plugs: Whales may turn down their hearing sensitivity when warned of an impending loud noise." ScienceDaily. ScienceDaily, 8 May 2012. <www.sciencedaily.com/releases/2012/05/120508151954.htm>.
Acoustical Society of America (ASA). (2012, May 8). Built-in ear plugs: Whales may turn down their hearing sensitivity when warned of an impending loud noise. ScienceDaily. Retrieved September 15, 2014 from www.sciencedaily.com/releases/2012/05/120508151954.htm
Acoustical Society of America (ASA). "Built-in ear plugs: Whales may turn down their hearing sensitivity when warned of an impending loud noise." ScienceDaily. www.sciencedaily.com/releases/2012/05/120508151954.htm (accessed September 15, 2014).

Share This



More Plants & Animals News

Monday, September 15, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Conservationists Face Uphill PR Battle With New Shark Rules

Conservationists Face Uphill PR Battle With New Shark Rules

Newsy (Sep. 14, 2014) — New conservation measures for shark fishing face an uphill PR battle in the fight to slow shark extinction. Video provided by Newsy
Powered by NewsLook.com
Shocker: Journalists Are Utterly Addicted To Coffee

Shocker: Journalists Are Utterly Addicted To Coffee

Newsy (Sep. 13, 2014) — A U.K. survey found that journalists consumed the most amount of coffee, but that's only the tip of the coffee-related statistics iceberg. Video provided by Newsy
Powered by NewsLook.com
'Magic Mushrooms' Could Help Smokers Quit

'Magic Mushrooms' Could Help Smokers Quit

Newsy (Sep. 11, 2014) — In a small study, researchers found that the majority of long-time smokers quit after taking psilocybin pills and undergoing therapy sessions. Video provided by Newsy
Powered by NewsLook.com
Spinosaurus Could Be First Semi-Aquatic Dinosaur

Spinosaurus Could Be First Semi-Aquatic Dinosaur

Newsy (Sep. 11, 2014) — New research has shown that the Spinosaurus, the largest carnivorous dinosaur, might have been just as well suited for life in the water as on land. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

    Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins