A neighbor who lives a couple of blocks away from me regularly fires up his old pickup truck in the wee small morning hours and allows it to idle for as long as 45 minutes before driving away. I occasionally awaken because of this, not because I hear the noise (which is far enough away to be only barely audible) but because I become aware of a rising nausea. I've never woken up nauseated without hearing the truck. As soon as that truck drives away, though, I feel better and usually drop back to sleep until the alarm rings. Is the sound making me sick?
Nothing ruins a good night's sleep faster than the sound of an old pickup truck, except maybe that of a leaf blower. In my case, I'll often lay there plotting complex revenge scenarios that would seem extreme even by Desperate Housewives standards. After a few cups of coffee, I'm a bit more pragmatic. I can rationally weigh more neighborly solutions that won't result in my next nap being inside the Ada County lockup. Judging by your kindly lack of vitriol, neighborly for you could mean offering to buy the guy a Prius. So, as your designated avenger, I'll simply hope that among the dozen or so nearby residents who are likewise assaulted, at least one schemer like me lies awake. One, that is, who's not so afraid of the county-issued orange jumpsuit.
As strange as it seems, there may be something to your nausea theory. Very low frequencies known as infrasound have been shown to cause symptoms like yours (plus headaches and dizziness), albeit with waves at much higher intensity than you're likely experiencing. These are sounds below most humans' ability to hear and will usually be felt as vibrations, if they are detected at all. Frequency of sound is measured in cycles per second, or Hertz (Hz); the higher the frequency, the higher we perceive the tone. Our ears can hear tones between 20Hz and 20,000Hz, and a truck engine ranges toward the lower end of that scale. It is conceivable that the pickup is also producing vibrations lower than 20Hz, and that you might be detecting and reacting to infrasound.
A curious aspect of lower frequencies is that they can travel very long distances in all directions by flowing along the ground. In nature, infrasound is produced by thunder, earthquakes and, under the right circumstances, even wind. Many animals can detect infrasound, and some can even produce it; elephants communicate over long distances using infrasound. There is growing evidence that this sensing ability provided an early warning during the 2004 Indian Ocean tsunami, resulting in a surprisingly high rate of survival of many native animals. Whales appear to use naturally occurring low frequencies to navigate, and have been known to stun squid with a blast of infrasound before dining (note to self: scratch Shamu from wedding reception guest list).
Air conditioners and other mechanical equipment in homes and office buildings occasionally produce low frequencies that include infrasound. Unfortunately, certain building structures are excellent conductors of indoor or outdoor infrasound—a possible contributing factor to your nausea. Worse yet, some studies demonstrate that mild to moderate hearing loss in the "conversational ranges" may make one more prone to react to low frequencies. Bad news comes in threes: Since the vibrations are conveyed not through your ears, but through your body, earplugs are relatively useless.
If infrasound is indeed causing your morning nausea, you may be more sensitive than most, but you are certainly not unique. Readers may recollect the odd stomach upset after standing near a giant bass speaker at a concert. At high intensity, virtually all people will suffer symptoms from infrasound. It doesn't take a conspiracy theorist to imagine military types looking into infrasound as weaponry, and there are fairly reliable reports suggesting they are. Among the ideas that may—or may not—have been implemented is a nausea-inducing device for crowd control. So far, though, the only openly documented sound weapon able to disperse an unlawful assembly seems to be the bagpipe.
In all sincerity, the pressing concern for you may be the psychological effects—incessant noise or vibration that can't be stopped or blocked can easily induce feelings of helplessness. So, I encourage you to find a way to convince the truck owner of the possible problem. If he won't change his ways, I'd consider helping out by standing on his lawn with my Highland Pipes, but the only garment I'm less inclined to wear than an orange jumpsuit is a kilt.
Dr. Ed Rabin is a chiropractor practicing at Life Chiropractic Center in Boise. Send orange-plaid Tam O'Shanters and health-related questions to firstname.lastname@example.org (on the Web at www.edrabin.com).