Date post: | 17-Dec-2015 |
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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