1. Sound Physics - Arrowhead Mr. Streufert 2013-14

2. Learning Targets A.Apply wave concepts to the physical and perceived characteristics of a sound wave  Perform calculations involving speed and intensity  Detect audibility and harmonic relationships

3. Learning Targets B.Relate waveform and FFT graphs to simple or complex sounds  Changes in Frequency  Identification of frequencies  Explain the multiple frequencies in a complex tone

4. Learning Targets C.Describe and explain sound phenomena  Resonance  Patterns of interference creating change in frequency  Doppler Effect

5. Learning Targets D.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

6. Learning Targets

7. Audibility Audibility: The ability for sound to be heard Sound Test Demonstration

8. Audibility Speed Frequency Wavelength

9. Audibility Infrasonic: Sounds below 20 Hz Ultrasonic: Sounds above 20,000 Hz

10. Audibility – Range of Hearing

11. 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

12. 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

13. Practice Question #1 If a sound seems to be getting louder, which of the following is probably increasing? – Intensity – Frequency – Speed of Sound – Wavelength

14. 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

15. Practice Question #3 A stereo speaker emits sound waves with a power output of 10 W. – What is the intensity (W/m 2 ) of the sound 10 m away? – What is the relative intensity (decibel level)?

16. 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/m 2 ?