sound physics - arrowhead mr. streufert 2013-14. learning targets a.apply wave concepts to the...
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SoundPhysics - Arrowhead
Mr. Streufert
2013-14
Learning TargetsA. Apply wave concepts to the physical
and perceived characteristics of a sound wave Perform calculations involving speed
and intensity Detect audibility and harmonic
relationships
Learning TargetsB. Relate waveform and FFT graphs to
simple or complex sounds Changes in Frequency Identification of frequencies Explain the multiple frequencies in a
complex tone
Learning TargetsC. Describe and explain sound
phenomena Resonance Patterns of interference creating
change in frequency Doppler Effect
Learning TargetsD. Calculate, predict and relate changes in the
sound characteristics that affect sound phenomena Calculate wavelengths and frequencies of sounds
produced by different instruments (strings, tubes, etc.)
Use interference patterns (standing wave analysis) Calculate the sound wave changes based on the
motion of the source and/or the observer
Learning Targets
Audibility• Audibility: The ability for sound to be
heard
• Sound Test Demonstration
Audibility
• Speed
• Frequency
• Wavelength
Audibility
• Infrasonic: Sounds below 20 Hz
• Ultrasonic: Sounds above 20,000 Hz
Audibility – Range of Hearing
Intensity• Intensity: The amount of power per
unit area– Need to know: • Power of the source of sound• Distance away from source
• Sound Waves travel outward from the source in a sphere
Intensity• Relative Intensity: The intensity of
sound in relation to the threshold of hearing–Measured in decibels– Based on a Logarithmic Scale• Measurements span a very large range of
values
Practice Question #1• If a sound seems to be getting
louder, which of the following is probably increasing?– Intensity– Frequency– Speed of Sound–Wavelength
Practice Question #2• Using the table on the Audibility
Handout, estimate the decibel level of the following sounds:– A cheering crowd at a football game– Background noise in a church– The pages of a book being turned– Light traffic on the road
Practice Question #3• A stereo speaker emits sound waves
with a power output of 10 W. –What is the intensity (W/m2) of the
sound 10 m away?–What is the relative intensity (decibel
level)?
Practice Question #4• What is the power of a sound source if the
intensity at 2.8 m is 5.4 x 10-3 W/m2?