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Le 9 novembre 2015, 07:05 dans Humeurs 0

canceling Headphones Work One man's noise is another man's music, but no matter what your taste, ambient noise is the enemy. Luckily, there's a piece of audio equipment designed especially to maximize your listening experience, keeping ambient noise out without sacrificing your music's sound quality. That piece of equipment is the headphone, and in this article, we're going to look at how headphones, especially noisecanceling headphones, work. Bose introduced the first noisecanceling headphones a decade later.

In order to understand headphones, you must first understand sound waves. You can check out How Speakers Work for some information, but we're also moncler outlet going to provide a brief introduction here.

When most people think of waves, they think of water waves, like you'd moncler outlet store seen in an ocean or lake. A shallow water wave is an example of a transverse wave, which causes a disturbance in a medium perpendicular to the direction of the advancing wave. You can see this relationship in the illustration below. The illustration also shows how waves form crests and troughs. The distance between any two crests (or any two troughs) is the wavelength, while the height of a crest (or the depth of a trough) is the amplitude. Frequency refers to the number of crests or troughs that pass a fixed point per second.


Sound waves have many of the same characteristics as water waves, but they are longitudinal waves, created by a mechanical vibration in a medium that produces a series of compressions and rarefactions in a medium. When you moncler outlet sale pluck a guitar string, for instance, it begins to vibrate. The vibrating string first pushes against air molecules (the medium), then pulls away. This results in an area where all of the air molecules are pressed together and, right beside it, an area where air molecules are spread far apart. As these compressions and rarefactions move from one point to another, they form a longitudinal wave, with the disturbance in the medium moving parallel to the direction of the wave itself.

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Le 9 novembre 2015, 06:50 dans Humeurs 0

How to Run a 5K in the Cold A 5K race moncler uk store moves quickly, with many average runners finishing in 30 to 45 minutes, but even a short time in cold temperatures exposes you to potential dangers. Most races start early in the morning when the temperatures are at the lowest. When possible, do your training runs at the same time as the race so your body is used to both the time and temperature. If you normally run indoors on a treadmill, move some of your training runs outdoors in colder temperatures. Multiple layers aid in keeping your body warm. If you get overheated during the race, you can remove top layers to cool off. Wear a synthetic inner layer to help pull the sweat away from your body. If your clothes are wet, you more likely to feel chilled. Wear an outer windproof layer for added warmth, especially on cold, windy days. Choose sweatwicking socks to keep your feet dry. Some running shoes moncler uk sale are highly ventilated, allowing cold air to reach your feet. Choose shoes with less ventilation to keep your feet warm. Since the 5K is such a short distance anyway, you want your body as warm as possible when you start so you don spend the first half of the race warming up. Stay out of the cold as long as possible. Arrive right before the race or park nearby so you can stay in your warm car until the race starts. Prepare yourself mentally for a slower pace during the race due to the cold temperatures, especially if you not used to winter running. Watch for icy patches and snow in winter running conditions. One misstep on a slippery surface can cause you to fall or injure yourself. Although dehydration is less of an issue for short runs in cold weather than it would be in warm weather, you still need to hydrate properly during and after the race. Not all moncler uk 5K races offer a water station, so bring your own water. After finishing the race, change into dry, warm clothing. You initially feel warm from the running, but the cold temperatures soon cause a chill, especially when your clothes are wet.