SOUND Science

What Makes Sound? vibration – a back and forth movement. To produce sound an object must be vibrating. energy transfer Speech is produced by vibration of vocal chords.

How Does Sound Travel? Sound is a vibration that travels through matter. As vibration occurs, molecules in the air squeeze together and then spread apart. compression – the part of sound wave where molecules are crowded together rarefaction – the part of the sound wave where molecules are spread apart

sound wave – a vibration that spread away from a vibrating object.

How Do You Hear Sound? Outer Ear – Acts like a funnel to direct sound waves to the eardrum Middle Ear – The vibrating continues on to the hammer, anvil, and stirrup Inner Ear – The vibrating continues to a fluid filled tube Nerve to Brain – Hair cell vibrations from tube pass on to the auditory nerve and onto the brain.

Your Ear!

Can Sound Travel Through Anything? Sound can travel through all forms of matter (including solids and liquids).

How Can You Change a Sound? pitch – how high or low a sound is Higher pitched sounds will have a greater frequency of sound waves. frequency – the number of times an object vibrates per second hertz – a unit for measuring frequency

What Makes Sound Loud? Energy of Sound Waves Decibels – a unit for measuring loudness Loudness is the human perception of the energy waves carry.

How Is Sound Recorded? Step 1: Change Sound Into Electric Current Step 2: Make the Current Stronger Step 3: Change Current to Magnetic Pattern When you speak molecules are colliding!

Do Sounds Bounce? reflection – the bouncing of a sound wave off a surface Example – the crack of the baseball bat absorption – the disappearance of a sound wave into a surface Example – the sound of a baseball hitting the glove

What Is An Echo? echo – a reflected sound wave

What Can Echoes Do? Sonar navigation – maps out the ocean floor Echolocation – the finding of an object by using reflected sound Example – Whales and dolphins use this to find objects Example – Bats use this to find their prey

How Do Moving Sounds Change? Doppler effect – the change in frequency (and pitch) as a source of sound moves toward or away from you. As you move away from a building the siren will sound lower.

What’s the Difference? Quality – the difference you hear in two sounds of the same loudness and pitch Fundamental frequency – the lowest frequency at which an object vibrates Overtone – the number and intensity overtones produces by each instrument give the instrument their distinctive sound. Resonance can be used to amplify sound. Music- a combination of sounds with distinct pitches and patterns.