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Transcript of Sound Waves
Sound is kinetic energy that moves from molecule to molecule. Because of this, higher temperatures mean more energy, more movement, and sound waves traveling faster than in the cold.
Speed of Sound
room temperature: 346 m/s
at freezing: 331 m/s
45 degrees C (113F): 358 m/s
How we Hear
Facts of the Human Auditory System
ears and hearing are fully developed at birth
infants respond to sound even before birth
ears respond to both loud sounds like a jet engine and soft sounds like a whisper. The jet engine is 1 trillion times more powerful than the whisper.
babies are born knowing the sound of their mother's voice
The closer the molecules are, the less time it takes the vibrations to transfer. Therefore, it is easier for vibrations to pass through solids than liquids and gases.
Elastic properties are the variables between materials that affect things like sound. Materials that are more rigid (like steel) that go back to their original positions faster are ready to vibrate again sooner than a material like rubber.
and what affects them
Questions I asked
Does (and how) temperature affect sound waves?
How do humans hear sound waves?
Do other things affect sound waves?
Can they travel through outer space?
How different is the speed of sound in water than air?
by Rose Sears
How I got interested...
My curiosity was born on a cold January night when my sister was singing in the car ride home. The thermometer read 6 degrees Fahrenheit outside, but it was warmer than that inside the car with the heat turned up. I wondered, "does temperature affect sound waves? Would my sister's voice sound different if we were outside in the cold?" and other questions filled my brain.
The speed of sound is affected by temperature, humidity, and air pressure
Speed of sound in
Density of those materials
Materials that are denser because they have larger molecules transmit sound slower because it takes more energy to make them vibrate.
Gold and aluminum have the same elastic properties. Aluminum is less dense than gold. Sound travels two times faster in aluminum than gold.
Sound travels faster through denser air because the molecules are closer together than in thinner air.
I don't want to listen to you
Sound in Space
Sound cannot travel through space because there is nothing for it to pass through. Sound simply can't exist if there isn't anything for it to travel through.
Hello? Why can't I hear myself talking?
Scientists have found a black hole in the distant Perseus galaxy cluster 250 million light years away singing a single B flat 57 octaves lower than middle C on the piano and one million billion times lower than the lowest audible sound to the human ear. These sound waves were able to travel through space because there was gas throughout the Perseus Cluster. Sound waves that travel through space may be the key to finding out how galaxy clusters grow, which are the largest structures in the universe.
I'm singing a beautiful song with just one note
Water vs. Air
Sound moves faster in water (1500 m/s) than in air (340 m/s) because they have different mechanical properties.
The temperature also affects the speed of sound in the water. Closer to the surface where the sun shines and the temperature is higher, the sound travels faster than in the cold, deep water away from the sun.
Measuring those Sound Waves
We describe high or low volumes as amplitude or intensity. Usually, in the same material, the intensity level in the decibel scale (dB) refers to powers of ten, increasing exponentially. We cannot use this to compare sound in water and air because, for instance, 150dB in water does NOT equal 150dB in air. Instead we use Watts per m squared.
Wavelength and Frequency
Wavelength and frequency are related because with a lower frequency comes a longer wavelength.
The Next Step
Now that I have this new knowledge of sound waves, every day when I hear things I understand the theory behind sound waves and how they work better than I did before this project. The next time my sister is in the car singing (annoyingly, of course) I know that if it were colder the sound would travel slower, even if it's hard to hear the difference. I now also understand why we have to warm up our instruments before we play them in band.
After this project, I want to research who discovered sound waves. In addition, I think researching deafness would be very interesting. Who knows, maybe someday we will be able to completely cure deafness.
The way I do my research has been refined by this project. I better know how to pick reasonable websites and how to choose key terms wisely.