Presentation on theme: "If a tree falls in a forest, and no one is around to hear it, did it make a sound?"— Presentation transcript:
If a tree falls in a forest, and no one is around to hear it, did it make a sound?
What is sound? Sound is a form of energy, just like electricity and light. Sound is made when air molecules vibrate and move in a pattern called waves or sound waves.
Think of when you clap your hands, or when you slam the car door shut. That action produces sound waves, which travel to your ears and then to your brain, which says, "I recognize that sound."
Sound is created by vibrations that produce waves of energy that move through matter
Vibration: a back and forth movement (that causes sound)
*ALL sound is caused by vibration!
The vibrations travel in waves away from the object. Sound Wave: a longitudinal wave caused by vibrations traveling through a medium.
Sound Waves are longitudinal (compressional) waves. The molecules are being pressed together as the sound waves move through matter. Longitudinal waves travel through the springs just like sound waves travel through the air.
Compression: the part of a sound wave where the molecules are crowded together Rarefraction: the part of a sound wave where the molecules are spread apart
Medium- a substance through which a wave can travel.
Properties of Sound
Pitch Pitch = how high or low a sound is
Properties of Sound frequency Pitch depends on frequency
Remember that Frequency is… the number of waves that pass by a point each second
Properties of Sound Larger frequency = higher pitch Smaller frequency = lower pitch slinky demo
High Pitch vs Low Pitch Flute http://www.youtube.com/watch?v=weTVPmWnlKE Trombone http://www.youtube.com/watch?v=bcwMovQ6US0
Notice the amplitude (volume)is the same, but the pitch changes. Low frequency Low Pitch Medium frequency Medium Pitch High frequency High Pitch how do you think opera singers can break glass when hitting high notes?
Pitch that “Hertz” hertz Pitch is measured in hertz (Hz)
Humans can hear sounds that vibrate between 20 times a second (20 Hertz) to about 20,000 times a second (20,000 Hertz).
Ultrasonic: a sound that is HIGHER than 20,000 Hz
Ultrasonic: a sound that is HIGHER than 20,000 Hz Examples: Bats Dogs Dolphins
Infrasonic: a sound that is LOWER than 20 Hz
Infrasonic: a sound that is LOWER than 20 Hz Examples: ElephantsWhales
http://ww w.youtube. com/watch ?v=AXhR mv1mrs4 Can you hear this? short clip http://www.yout ube.com/watch? v=VxcbppCX6Rk http://www.you tube.com/watch ?v=H- iCZElJ8m0 Can you hear this? medium length clip Can you hear this? longest clip
Properties of Sound Loudness Loudness measures how well a sound can be heard.
Properties of Sound Loudness depends on amplitude