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Why Do Some Sounds Make People Sick?

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While playing music too loudly can damage hearing, there are other things you should know about the effects of some sounds on the human body.

Decibels are used to measure the intensity of sounds (prolonged exposure to sounds above 85 dB can cause hearing loss), and frequency, which is measured in Hertz (Hz), refers to the amount of times a sound wave occurs each second. Human ears can generally pick up on sounds that fall in the 20Hz to 20KHz range. Frequencies above that are called ultrasonic, and frequencies below 20Hz are sometimes referred to as infrasonic. Infrasonic sound is both naturally occurring (earthquakes, ocean waves, upper-atmospheric lightning, etc.) and man-made. Some studies have shown that at high intensities, infrasonic sounds can have extra-aural bioeffects, including nausea, headaches, and dizziness, but why? The short answer: bad vibrations.

Sound is a wave of pressure traveling through a medium. Infrasonic sound, for example, has a long wavelength that, according to Popular Science, “makes it much more capable of bending around or penetrating your body, creating an oscillating pressure system.” Every object, including parts of the body, has a natural frequency at which it vibrates, a phenomenon known as resonance. Popular Science has more to say about how low-frequency resonance affects the body:

“Human eyeballs are fluid-filled ovoids, lungs are gas-filled membranes, and the human abdomen contains a variety of liquid-, solid-, and gas-filled pockets. All of these structures have limits to how much they can stretch when subjected to force, so if you provide enough power behind a vibration, they will stretch and shrink in time with the low-frequency vibrations of the air molecules around them.”

A 1983 study on human body vibration exposure published in The Journal of the Acoustical Society of America found that

“exposure to vertical vibrations in the 5-10 Hz range generally causes resonance in the thoracic-abdominal system, at 20-30 Hz in the head-neck-shoulder system, and at 60-90 Hz in the eyeball. When vibrations are attenuated in the body, its energy is absorbed by the tissue and organs...Vibration leads to both voluntary and involuntary contractions of muscles, and can cause local muscle fatigue, particularly when the vibration is at the resonant-frequency level. Furthermore, it may cause reflex contractions, which will reduce motor performance capabilities.”

Other studies suggest that low-frequency noises, like those produced by wind turbines, trigger a reaction in the brain that could lead to adverse health effects. The frequencies have also been linked to changes in respiratory rhythms due to chest-wall vibration, with varying results depending on whether the subject is standing or sitting (resonance occurs at different levels depending on body position). Infrasound has been used at haunted houses to make visitors feel uneasy, and some believe that there is a “brown note” (around 9Hz) that could cause bowels to release (though this was “busted” by Adam Savage and Jamie Hyneman on Mythbusters).

More research is needed to fully understand why some people are affected and others are not, but engineers have been developing sound-dampening technology for turbines, and some doctors have suggested that noise-canceling headphones may help in other cases.

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Big Questions
What Do Morticians Do With the Blood They Take Out of Dead Bodies?
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Zoe-Anne Barcellos:

The blood goes down the sink drain, into the sewer system.

I am not a mortician, but I work for a medical examiner/coroner. During an autopsy, most blood is drained from the decedent. This is not on purpose, but a result of gravity. Later a mortician may or may not embalm, depending on the wishes of the family.

Autopsies are done on a table that has a drain at one end; this drain is placed over a sink—a regular sink, with a garbage disposal in it. The blood and bodily fluids just drain down the table, into the sink, and down the drain. This goes into the sewer, like every other sink and toilet, and (usually) goes to a water treatment plant.

You may be thinking that this is biohazardous waste and needs to be treated differently. [If] we can’t put oil, or chemicals (like formalin) down the drains due to regulations, why is blood not treated similarly? I would assume because it is effectively handled by the water treatment plants. If it wasn’t, I am sure the regulations would be changed.

Now any items that are soiled with blood—those cannot be thrown away in the regular trash. Most clothing worn by the decedent is either retained for evidence or released with the decedent to the funeral home—even if they were bloody.

But any gauze, medical tubing, papers, etc. that have blood or bodily fluids on them must be thrown away into a biohazardous trash. These are lined with bright red trash liners, and these are placed in a specially marked box and taped closed. These boxes are stacked up in the garage until they are picked up by a specialty garbage company. I am not sure, but I am pretty sure they are incinerated.

Additionally anything sharp or pointy—like needles, scalpels, etc.—must go into a rigid “sharps” container. When they are 2/3 full we just toss these into one of the biotrash containers.

The biotrash is treated differently, as, if it went to a landfill, then the blood (and therefore the bloodborne pathogens like Hepatitis and HIV) could be exposed to people or animals. Rain could wash it into untreated water systems.

This post originally appeared on Quora. Click here to view.

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Why Does Asparagus Make Your Pee Smell Funny?
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The asparagus has a long and storied history. It was mentioned in the myths and the scholarly writings of ancient Greece, and its cultivation was the subject of a detailed lesson in Cato the Elder's treatise, On Agriculture. But it wasn't until the turn of the 18th century that discussion of the link between asparagus and odorous urine emerged. In 1731, John Arbuthnot, physician to Queen Anne, noted in a book about food that asparagus "affects the urine with a foetid smell ... and therefore have been suspected by some physicians as not friendly to the kidneys." Benjamin Franklin also noticed that eating asparagus "shall give our urine a disagreeable odor."

Since then, there has been debate over what is responsible for the stinky pee phenomenon. Polish chemist and doctor Marceli Nencki identified a compound called methanethiol as the cause in 1891, after a study that involved four men eating about three and a half pounds of asparagus apiece. In 1975, Robert H. White, a chemist at the University of California at San Diego, used gas chromatography to pin down several compounds known as S-methyl thioesters as the culprits. Other researchers have blamed various "sulfur-containing compounds" and, simply, "metabolites."

More recently, a study demonstrated that asparagusic acid taken orally by subjects known to produce stinky asparagus pee produced odorous urine, which contained the same volatile compounds found in their asparagus-induced odorous urine. Other subjects, who normally didn't experience asparagus-induced odorous urine, likewise were spared stinky pee after taking asparagusic acid.

The researchers concluded that asparagusic acid and its derivatives are the precursors of urinary odor (compared, in different scientific papers, to the smell of "rotten cabbage," "boiling cabbage" and "vegetable soup"). The various compounds that contribute to the distinct smell—and were sometimes blamed as the sole cause in the past—are metabolized from asparagusic acid.

Exactly how these compounds are produced as we digest asparagus remains unclear, so let's turn to an equally compelling, but more answerable question:

WHY DOESN'T ASPARAGUS MAKE YOUR PEE SMELL FUNNY?

Remember when I said that some people don't produce stinky asparagus pee? Several studies have shown that only some of us experience stinky pee (ranging from 20 to 40 percent of the subjects taking part in the study, depending on which paper you read), while the majority have never had the pleasure.

For a while, the world was divided into those whose pee stank after eating asparagus and those whose didn't. Then in 1980, a study complicated matters: Subjects whose pee stank sniffed the urine of subjects whose pee didn't. Guess what? The pee stank. It turns out we're not only divided by the ability to produce odorous asparagus pee, but the ability to smell it.

An anosmia—an inability to perceive a smell—keeps certain people from smelling the compounds that make up even the most offensive asparagus pee, and like the stinky pee non-producers, they're in the majority.

Producing and perceiving asparagus pee don't go hand-in-hand, either. The 1980 study found that some people who don't produce stinky pee could detect the rotten cabbage smell in another person's urine. On the flip side, some stink producers aren't able to pick up the scent in their own urine or the urine of others.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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