Sound Physics - Arrowhead Mr. Streufert 2013-14. Learning Targets A.Apply wave concepts to the...

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?