'Whales can't even hear naval sonar' says Navy boffin

[FarCenter]

By Lewis Page • http://www.theregister.co.uk/2009/11/25/navy_sonar_whale_ct_scan/

A boffin funded by the US Navy has used a gigantic CT scanner, normally employed for inspecting space rockets, to X-ray the head of a whale. The results apparently indicate that naval sonars can't be the cause of whale beachings, as the mighty cetaceans are unable to hear the relevant frequencies.

The boffin in question is Dr Ted Cranford, whale expert at San Diego State University. He describes what he does in this way:

My work focuses primarily upon the functional morphology of biosonar, particularly sound generation and transmission, but also sound reception in toothed whales. I like to combine technological tools and traditional anatomic techniques to develop new or innovative methods to interrogate the structure/function complex.
One technological tool the doc has put to use is "a giant CT scanner, originally designed to inspect solid-fuel rocket motors".

"After scanning the head of a sperm whale, I subsequently reconstructed it using 3-D computer graphics tools to gain virtual access to the internal in situ anatomic geometry," reports Cranford, whose work is sponsored in part by the Office of Naval Research and the Chief of Naval Operations' Environmental Readiness Division.

Both these organisations have a deep interest in the details of whales' bio-sonar abilities, as it is frequently suggested by environmentalist groups that naval sonar confuses or distresses the mighty creatures - perhaps causing tragic beaching incidents. Similar claims are made with respect to dolphins.

But the ONR announced yesterday that Cranford's latest findings "suggest that mid-frequency active sonar sounds are largely filtered, or 'muffled', before reaching the animal’s ears. The findings also suggest that higher frequencies used by whales to hunt prey are heard at amplified levels without any dampening."

<SNIP>
This could be good news for whales and dolphins both, as it might mean that media and environmentalist attention will shift away from naval operations and away from beachings - a very minor problem for cetaceans - onto rather more serious problems. Commercial fishing, for instance, is thought to kill 1,000 marine mammals every day.

On the other hand, given the traditionally strong linkage between whale/dolphin activism and dislike of the military, possibly not.

[John N Morgan]

1. I can't hear microwaves, but they can still cook me ... just say'n

[hlthe2b]

3. Exactly... How do we know the sonic effect is auditory?

Geeus... I just love these paid biostitues (as Robert Kennedy, JR and Mike Papantonio like to term them)

[Buzz Clik]

2. The article quoted in the OP is far more definitive sounding than Cranford intends.

Nowhere does Cranford say that naval sonar cannot be heard by whales.

A less snarky and far more objective report of Cranford's findings can be found here.

[eShirl]

4. boffin...

In the slang of the United Kingdom, Australia, New Zealand, India and South Africa, boffins are scientists, engineers, and other people engaged in technical or scientific research. The word 'boffin' (or 'boff' - often as an insult) can also be used to refer to any particularly clever person. The closest American equivalent is "egghead".
http://en.wikipedia.org/wiki/Boffin

[DCKit]

5. I can't "hear" subsonics either, but they'll damage my ears just the same.

An ultrasound during pregnancy releases the equivalent of 110 decibels on the fetus and evolution is (just) a theory.

Guess we'll just have to wait and see.