Lesson 5: Understanding the Nature of Sound

Chapter 2: Lesson 5: Understanding the Nature of Sound You can understand the nature of sound by studying how sound waves move through matter.Sound - form of energy you can hear; a vibration that travels through matter in the form of waves.Vibration- the back and forth movement of particles in matterSound Waves - carry vibrations forward from one pace to anotherWavelength - the distance between one part of a wave and the same part of the next waveFrequency- the number of waves moving past a point in one second When a musician strums the guitar, you hear music. But how are sounds created? And how does sound get your ears? Sound is produced when movement causes a vibration. When a musician strums the guitar, the strings move back and forth, or vibrate. This vibration hits air particles in front of the strings, making the air vibrate as well. The vibration passes from particle to particle a moves forward through the air. Sound moves by making particles vibrate. But sound doesn't carry particles all the way from the source of the sound to your ear. The particles simply move back and forth in the form of a wave. Sound needs to travel through matter, such as air, liquid, or a solid. Without particles, sound cannot travel. Sound wavescarry energy from one place to another. Energy from the string’s vibration transfers to air particles. These particles move forward and air particles crowd together. This region of a sound wave is called a compression. Here the air pressure is greater than normal. After the energy is passed to neighboring particles, the air pressure decreases. The particles move apart. This region of a sound wave is called a rarefaction. A wave is described by its wavelength and frequency. Wavelength is the distance between one compression and the next, or one rarefaction and the next. Frequency is the number of waves moving past one point in one second. Wavelength and frequency are related. Waves with short wavelengths have a high frequency. High-frequency wave sound high to us, like the sound of a siren. Low-frequency waves sound low, like the sound of a bass guitar. Low-frequency sounds are produced by waves with long wavelengths. A sound is loud or soft depending on its amplitude. The amplitude of a sound wave is the size of the original vibration, like the distance a guitar string is pulled. The small vibration produces a sound wave with small amplitude. So the music you hear sounds soft. Loud sound is produced by large amplitude. What is vibration? What kind of matter can a sound wave travel through? What happens during compression? How does a sound wave travel through air? Does low-frequency sound have short or long wavelength? short long What causes a sound to be produced? What happens when a vibration hits a particle? What is one way to measure wavelength? What happens when a sound wave from a playing trumpet hits an air particle? the particle moves up and down the particle turns around and around the particle moves back and forth the particle does not move Of these musical instruments, which could produce a sound with the shortest wavelength? violin kettle drum bass guitar tuba During rarefaction, particles are... spread out under pressure pushed forward vibrating quickly If series A represents sound waves from a ringing school bell, what might the sound waves from series B represent? growling lion shrieking siren person screaming high note of a flute A decrease in amplitude leads to a decrease in... wavelength frequency volume compression