SoundChapter 17

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

https://www.youtube.com/watch?v=cNSx1RdPl04

https://www.youtube.com/watch?v=eb9xuYKJVeo

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

Just Like Me

• Country?• Rap?• Metal?• Pop?• 80’s?• 90’s?• Alternative?• Boy Bands?

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

Overtones

•The higher frequencies produced by a vibrating object

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

Reverberation

•Repeated echoes of sound because of a hard surface

The Outer Ear•Collects sound and directs to ear canal- reason ear is shaped like a funnel

The Middle Ear• Sound waves reach middle and vibrate the eardrum• Transmits vibrations to 3 small connected bones-

hammer, anvil, and stirrup

The Inner Ear

• Fluid filled part of ear•Different sounds vibrate in different ways