Sound Notes Chatfield Senior High Department of Physics.
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Transcript of Sound Notes Chatfield Senior High Department of Physics.
Sound Notes
Chatfield Senior High
Department of Physics
Sound is a Wave
It is a longitudinal
(1-D) wave
Properties of Sound
Transmission-sound goes through a material
Reflection- waves bounce off at the same angle it was received
Absorption- waves are blocked by a substance (opposite of transmission)
Transmission in space?
Sound requires a medium to travel
Speed of Sound
It is variable based upon temperature and density of the material
Approximate values of speed of sound Air (00-) 330 m/s Air (25o) 343 m/s Water-1440 m/s Glass-4550 m/s Iron and Steel- 5000m/s
Lab 1- Verifying frequency of a tuning fork
Determine period of wave by averaging 10 wavefronts as below and then use f=1/T to
verify frequency
FFT Curve
Lab 2-Sound through echo
Find distance of the tube and double it (why?) Use v=d/t to determine the speed of sound in
air.
Lab 3-Finding Resonance of Tube Find frequency where sound rings out The sound is reflecting off the water and
therefore creates a closed ended tube The is basically a quarter of a wavelength
(why?)
Resonance in Sound
Wavelengths that have the same amplitude and frequency that result in an increase of amplitude
Closed Ended Tube (Pipe organ)
Open-Ended Tubes and Strings(Organ / Guitar String) (1/2
The decibel
A logarithmic scale that shows the loudness of soundL=10 A A= log L
Table of valuesThreshold of hearing- 0 dBWhisper-20 dBLibrary-40 dBRefrigerator-45 dBRestaurant- 50 dBOrdinary Conversation-65 dBBusy Traffic- 70 dBScreaming Child- 90 dBiPod at Maximum Volume-108 dBCSH Fire Alarm-115 dBThreshold of Pain-120 dBJet Airplane-140 dB
Frequencies of Sound
The human ear hears sound from the range from 20-20000 Hz
We hear sounds the best from 1000-5000 Hz
Frequencies of Music
Range of Audibility of the Human Ear
Ultrasound (Frequencies above human hearing)
Beats
Two waves constructively interfering whose frequencies are above or below each other
The Ear
Function of the Ear’s parts
Outer ear-pinna-collects sound Middle ear-transmits vibrations to the
inner ear Inner ear-fluid transmitted to hair cells
that have nerve endings (also used for balance)
Doppler Effect
When an object is moving toward the observer the pitch is higher
When an object is moving away from the observer the pitch is lower
Sonic Boom
Sound and Music
Most pure…the Blue Man Group