|
The art of making music by running a bow against a saw arose in several countries around the world when steel saws became widely available some 300 years ago. In the United States it originated in the Appalachian Mountains and reached a peak in popularity in the vaudeville acts of the 1920s and 1930s but faded towards the second world war. However, the art still endures on today maintained alive by many performers. The sound produced by a musical saw occurs as a result of the friction exerted by the bow upon the saw which causes the steel surface to vibrate, much in the same way as the string of a guitar vibrates when plucked. These vibrations produce compression waves in the surrounding air which are transmitted to our ears and are perceived as sound. In a guitar, the pitch of the vibrating string can be adjusted by reducing its effective length, which guitarists do by pressing their fingers to the string. In the musical saw, something similar happens when the performer bends and twists the surface of the saw. This creates bounds that restrict the vibrations and changes their pitch in relation to where the bow is applied. The mathematics of the sounds produced by musical saws is quite complex. In the video below, former university professor turned street performer, Robert (The Saw Man) Maddox, plays Somewhere My Love (Lara’s theme from the movie Dr. Zhivago) in downtown Knoxville, Tennessee.
0 Comments
Besides clapping your hands and snapping your fingers, there is another way to make sounds with your hands. The approach I show in the video below exploits the facts that the palms of your hands are concave, and that when you place your hands opposite to each other and introduce a slight twist, the area around your palms acts like a seal turning both of your hands into suctions cups. Once you have arranged your hands in this position, you can press them against each other forcing out the air between them which will make a sound. The expelling of the air will create a low pressure area (not a vacuum, see below) between your hands, and when you break the seal, the air will rush back in and produce another sound. By pressing and releasing your hands repeatedly against each other you can rapidly produce rhythmical sounds. It is important to understand that the reason air rushes in when you break the seal is not that the air is “sucked in” by the vacuum in between your hands. As I have explained in my blog, vacuums don’t suck; it is the atmosphere that pushes. A column of air hundreds of miles high above you excerpts a pressure of 14.7 pounds per square inch (at sea level) on your hands. When you move your hands or fingers and break the seal, it is all that pressure that pushes the air back in. While clapping hands and snapping fingers are well known descriptions of how to make sounds with your hands, I don’t know what word to use to describe the method that I used in the video to produce sounds with my hands. If you know or want to suggest (or invent) a verb for it, please leave a comment below! There are many stories of singers breaking a wine glass with their voice. These stories are true, and it has to do with the singer being able to make a loud enough sound near the wine glass at what is called the “resonant frequency” of the wine glass. This is the frequency at which the sound waves impacting the wine glass will make it vibrate the hardest. When this state is achieved, the wine glass will be subjected to a strong structural stress that will often shatter it as shown on the video below. This post has nothing to do with breathing the same air as Kings, Queens, or other aristocrats. It is actually about breathing the so called Noble gases, Helium, Neon, Argon, Krypton, and Xenon. This crazy experiment performed in the video below by Cody from Cody’s Lab is not without risk (even though these gases are elements that are quite unreactive), so don’t try it at home! If you want to skip ahead to the time in the video where he starts breathing the gases, it occurs at minute 4:16. As you saw in the video, his voice went from a seemingly very high pitch after breathing the lightest gas, Helium, to a seemingly very low pitch after breathing the heaviest gas, Xenon. This is because Helium is lighter than air and the sound waves produced by the vocal chords propagate faster through it. This has the effect of amplifying the high-pitch components of the voice. With Xenon, sound waves travel slower, and this has the opposite effect. However, what is really affected by the gases is not so much the pitch of the sound but its overall quality or timbre. In the video below Physics Girl uses a vibrating plate and sand to create cool patterns called Chladni Figures, named after the German physicist Ernst Chladni who studied these patterns in the 18th century. |
Categories
All
Archives
August 2024
|
RSS Feed