Small engines like 2-strokes on bikes benefit from lower back pressure, but taking the muffler off a car engine can make it run much worse, as the exhaust is "overscavenged."

The same technology that's used on military helicopters to quiet their blades has been sold on dirt bikes to muffle their engines: active cancellation. A microphone and speakers are used to emit a signal that's out of phase with the engine noise, but only in a specified direction.

Active cancellation doesn't absorb any acoustic energy, it just points nulls in the important directions, like in a horizontal plane for a bike, or out in front of a chopper. The overall effect is to increase the noise coming from the source; it's just redirected in less obtrusive directions.

http://www.freepatentsonline.com/EP0725965.html

I have visited that particular wind energy installation three times since it was placed in service six months ago. The "noise" they're talking about is a low whooshing sound that registers about 42 dBa from 1,000 feet. That's about 8-10 dBa above ambient sound levels at night, unless the crickets are chirping, the cows are mooing, a dog is barking, a car is driving by, rain is falling, or the leaves are rustling from the same wind. Or something else.

When the windows are closed, they are inaudible from inside a house. End of story.

What we have here is a handful of unhappy people who project their anxieties on changing circumstances. Wind turbines happen to be a highly visible symbol of change. So, if they're feeling stressed, or have an upset stomach, or couldn't get to sleep last night, it's the turbines fault. Very convenient. Of course, this is not an attitude that will come in handy during the Long Emergency.

Michael (WI)

Not to worry. Someday at $10/gallon cars will be eerily quiet.

If you take off mufflers you can make small improvements in efficiency but it tends to work well at high engine RPMs when the engine is flowing more air. Cruising conditions are not really impacted by the mufflers. All out race cars therefore do not use mufflers as they make more power by means of being more efficient, but the difference is relativley small (small differences make are a big deal in racing).

Its certainly not enough to solve the dilema, but its apparent that there is no single solution.

Aside from the massive amount of noise from the roads, I think most people would be miserable from the noise inside the car while driving along. If youve ever driven a car that didnt have mufflers on youd know how that is.

Reading that article about noise from a wind farm I was intruiged by the odd symptoms. The term pyschosomatic comes to mind. Next thing we know theyll be complaining of an odd taste to the water, aching bones, trembling hands and the first person who lives near a windfarm and gets cancer will cause renewed investigations. Maybe they would prefer to live next door to a coal power plant, or a nuclear plant? Or maybe they should just live without power for a while to learn to appreciate the windfarm?

Do wind turbines cause medical problems?

They have trouble sleeping, and Cheryl Meyer, 55, sometimes feels a fluttering in her chest. Gerry is sometimes nauseated and hears crackling.

I can attest to decades of dealing with these complaints in patients. It is my impression that these and other non-specific (abdominal pain, constipation, diarrhea, headache, myalgias....) are often symptoms of generalized distress which has not been properly identified and resolved.

It isn't that the symptoms aren't real -- they are-- or that they aren't distressing -- they certainly are that. They are the somatic perception of an environmental change that hasn't been fully understood or adapted to by the sufferers' autonomic nervous systems.

The "cure" isn't to avoid change-- that's unrealistic. Nor is it to do more and more CT scans and cardiac catheterizations and the like, looking for "organic disease" (which won't be found, and will lead the medical profession to assign the symptoms to the"functional" category and stop any further investigation, once the maximum revenue has been extracted in the search.) Nor is it to harangue people and shout at them for being so stupid.

The cure is to help people adapt. Everyone knows from personal experience that change is distressing, and that most people eventually adapt to the changes -- even drastic changes. A huge, unresearched field in clinical medicine is facilitation of adaptation. The current reductionist approach to disease ("one organism, one disease") has led to spectacular advances. But I believe that future gains will mostly come from understanding people's responses to their environment and the many and varied ways they cope with change.

I could just as well have said "dogs" instead of "people", as they are similarly exquisitely sensitive to environmental cues and just as prone to "neurotic" responses as human beings. All nervous systems seem to behave similarly.

TOD has got people thinking in terms of complex, interconnected and loop-back systems. How to acquire and transmit coping skills on a changing planet-- that is where the money is.

And yes, we need wind turbines. And I believe they have a stark beauty. I wouldn't mind one in my back yard.