Chapter 15: Sound Energy PowerPoint Name: Asit Sarker Teacher: Miss. Sansone

Table of Contents Cover Slide………………………………………………………………………………………….…1 What Causes Sound………………………………………………………………………….…..3 Sound Waves………………………………………………………………………………….…….4 Pitch and Frequency……………………………………………………………………….…….5 Volume………………………………………………………………………………………………...6 Reflection & Echo………………………………………………………………………………...7 Absorption…………………………………………………………………………………………...8 Doppler Effect……………………………………………………………………………….……..9 My Concept Web………………………………………………………………………………….10

What Causes Sound? Sound is made by a vibrating object. If there is no vibration there is no sound. You give the energy needed for it to vibrate. If a string vibrates the molecules of gasses the air next to it vibrate. Then the molecules squish together then spread apart.

Sound Waves If a vibration spreads away from the vibrating object it is a sound wave. If the things inside your ear vibrate it means a sound wave reached your ear Sound waves can travel through solid the best. Sound waves can travel through liquids the second best. Sound waves can not travel if there is no matter.

Pitch and Frequency The words that describe pitch is high and low. A number of times a object vibrates per second is called frequency. Hertz is the unit that measures frequency. Vibrations and sound waves are described frequency. Did you know that men mostly have longer and thicker vocal cords than women, so then men’s voices are tend to be lower pitched than women’s voices.

Volume The meaning of volume is how loud or soft it is. Decibels (dB) is the unit that measures volume with a device called decibel meter. If give more energy to sound it goes farther if you give less energy it goes a short amount of distance. You can make a sound louder by increasing the surface that vibrates. In a decibel scale when a sound measures up to 50 dB is 10 times more louder than one that measures 40 dB.

Reflection & Echo The meaning of reflection is when a sound wave bounces off a surface. The meaning of echo is a reflected sound wave. If you compare and contrast a ball hitting a towel and a ball hitting a metal sheet will be different. It will be different because sound waves act differently hitting a smooth, and hard surface. The amount of the sound wave reflecting off a surface depends on the kind of material. When you sing in a shower you might notice how good your voice sound. Because the bathroom walls are hard and smooth that’s why your voice sounds good.

Absorption The meaning of absorption is the disappearance of a sound wave absorbed in a smooth surface. If a sound wave is absorbed, it’s energy is changed into heat energy. Some part of the sound wave might come through the other side. When a sound wave hits a soft textured surface most of the energy is absorbed. When a ball hits a towel and the sound waves are absorbed you can’t mostly hear anything.

Doppler Effect The meaning of Doppler effect is when a source of a sound wave moves toward and away from you. If a siren comes toward you the sound waves crowd together. Then there are more than usual sound waves hitting you ear each second. So the frequency is higher and the pitch. Doppler effect is named after a 19th century scientist named Christian Johann Doppler.

My Sound Video My Concept Web Sound