Ever since the cold war era, sirens have been the prime warning signal for use during tornados or national threats. The main problem with the current sirens are that they are not intended to be audible from indoors or from a moving vehicle at a distance. The loudest siren made today, American Signal's T-135 has a 70 dB radius of around 11,000 feet. Most sirens, such as Federal's 2001 has a 70 dB radius of only 6200 feet.
During tests in 1982 at the Cincinnati/Northern KY International Airport, my toroidal whistle prototype achieved an 85 dB radius of 1 mile and a 70 db radius of 13,200 feet (2.5 miles). At 75 dB it was audible from the interior of a moving vehicle at 2 miles! A friend of mine heard the tests from his home in Delhi, OH, nearly 5 miles from the test site. This became US Patent 4429656. You'll see the test on the video link.
http://www.youtube.com/watch?v=jbhxzW21ejc
I was since awarded US Patent 4686928 on an inverted horn loaded toroidal whistle which is a full 10 dB louder than the prototype and promises a 70 dB radius of 4 miles (the 60 dB radius of my prototype)! One of these units could replace three of the American signal T-135 sirens or 9 of the Federal 2001 sirens!
The lower two links are to the patents themselves. I feel my inventions could not only provide the much needed improvement in coverage, but save in the high cost of replacing the currently ineffective warning sirens.
http://www.delphion.com/details?&pn=US04686928__ (Dynawhistle)
http://www.delphion.com/details?pn10=US04429656 (Ultrawhistle)
I would like for a manufacturer (hopefully from my home state of Kentucky) to build one of my Dynawhistles and test it in actual cities. I believe it would soon catch on, as unlike a siren of equal output, it would not sound unbearable to those within the first few hundred feet and would likewise be audible in areas and situations where no current siren would.