Sound Chapter 17. Sound Waves Caused by vibrations of molecules. The molecules bump each other and...
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Transcript of Sound Chapter 17. Sound Waves Caused by vibrations of molecules. The molecules bump each other and...
Sound Waves
•Caused by vibrations of molecules.•The molecules bump each other and the sound wave transfers energy.•Remember they are a type of compressional wave, so sound has to have matter to travel through.
https://www.youtube.com/watch?v=JVhYuqr03IQ
The Speed of Sound
•Travel at different speeds through different mediums•Because in a ________ the particles are closer together, sound travels faster in this type of matter.•Because particles in a warm substance move _________, sound travels faster in this temperature
Amplitude and Loudness
•Loudness: Human perception of how much energy a sound wave carries•Amplitude in compressional wave: The more compressed the compressions and the more spread out the rarefactions, the higher the amplitude.•Higher amplitude=more energy
The Decibel Scale
•Measures the loudness of sound•Hearing loss starts occurring at 85 dB•Amount of damage depends of frequency of sound and period exposed
Frequency and Pitch
•Pitch: how low or high it sounds•The higher the pitch, the higher the frequency•The higher the frequency, the smaller the _____________.
The Human Voice
•Vocal cords vibrate as you speak or sing.• The length and thickness of your vocal cords
determine the pitch of you voice.• Short or thin vocal cords= higher frequency/higher
pitch voices• Think or long vocal cords=lower frequency/lower
pitch voices
The Doppler Effect
•The change in frequency as the source of sound is moving relative to the listener.•Example: ambulance, chiming clock•Remember 6th grade science?
•As planets move away from us, their light is shifted to lower frequencies.
What color has a lower frequency in the rainbow? So this is called a _____ __________.
•As planets move toward us, their light is shifted to higher frequencies.
What color has a higher frequency in the rainbow?So this is called a _______ _________.
Music
•A group of sounds that have been deliberately produced to make a regular pattern.•Created by vibrations
Natural Frequency
•Every object will vibrate at a certain frequency•Depends on shape and size of the object, or instrument
Resonance
•Occurs when an object is made to vibrate at its natural frequencies by absorbing energy from a sound wave or another object vibrating
Stringed Instruments
•Pitch of the sound depends on the length, diameter, and tension of the string •Stringed instruments usually have a hollow chamber that amplifies the sounds•Example: guitar, piano, cello
https://www.youtube.com/watch?v=RxFNHeXKmrY
Percussion
• Instruments that are struck to make sound•Pitch depends on the length and tightness of the drumhead or bars•Example: Drums & xylophone
https://www.youtube.com/watch?v=eLiZwU0r0Lw
Brass and Woodwinds
• Instruments with pipes or tubes•Pitch depends on air column or length of pipes/tubes •Example: Flute, saxophone, clarinet, oboes
https://www.youtube.com/watch?v=PjkmmTZXRjU
The Middle Ear• Sound waves reach middle and vibrate the eardrum• Transmits vibrations to 3 small connected bones-
hammer, anvil, and stirrup