1. SOUND
Chapter 11

2. Review Terms Compression Rarefaction Longitudinal wave Medium
Wavelength
Amplitude
Frequency
Interference

3. New Things: Lesson 1 Sound wave: Vibration longitudinal wave
Can only travel through matter
Vibration
Rapid back-and-forth movement that can occur in matter (S, L, G)
ie: guitar string being pulled causes a disturbance in the air. There is energy in this disturbance that is carried outward from the source = sound wave

4. What Affects the Speed of Sound?
1) Density/stiffness of the medium
How closely particles are packed together
Temperature of the medium
Inc temp = Inc speed of sound FOR GASES
Why? Inc in energy in particles = more energy transferred
Dec temp = Inc speed of sound FOR LIQ & SOLIDS
Why? Dec in temp = particles closer together = faster for sound to travel throughout the medium

5. New Things, Lesson 2 Doppler effect: Intensity:
Change of pitch when a sound’s source is moving in relation to an observer
Source of sound is moving; observer is standing still
Intensity:
Amount of sound energy that passes through a square meter of space in 1 second

6. More New Things: Lesson 2
Pitch:
Perception of how high or low a sound seems
Resonance:
Increase in amplitude that occurs when an object vibrating at its natural frequency absorbs energy from a nearby object that is vibrating at the same frequency (1 ball of play-doh is added to an equal ball of play-doh to create a larger ball of play-doh)

7. Detecting Sound 1 Outer Ear Middle Ear Collects sound
Ear canal – directs collected sounds to middle ear
Middle Ear
Amplifies sound
Eardrum – sounds from outer ear cause eardrum to vibrate; vibrations transfer to 3 bones:
Hammer
Anvil
Stirrup
These bones conduct sound towards inner ear

8. Detecting Sound 2 Inner Ear
Turns sound waves into signals that can be recognized by the brain
Cochlea – small, fluid-filled chambers
Sound passing through cochlea causes tiny hair-like cells to vibrate;
movement of these cells produces nerve signals;
signals travel to brain;
signals interpreted as sound.

9. Decibel Scale dB
Describes the intensity (loudness) of a sound

10. Relationship btwn vocab terms
Frequency & wavelength
Longer wavelength = lower frequency
Shorter wavelength = higher frequency
Pitch & Frequency
Higher frequency = higher pitch
Lower frequency = lower pitch

11. Sound Interference
Constructive
Destructive
Beats

12. Beats How to calculate beats: The difference in frequencies
ie: a musician plays a note with a pitch of 400Hz; another musician plays a note with a pitch of 395Hz; the difference is 5 Hz; beats will occur 5 times per seconds

13. Fundamental & Overtones
Fundamental – lowest frequency that a material naturally vibrates
Overtones – higher frequencies at which the material vibrates
Timbre (TAM-bur) – caused by the interferences of these waves, unique to each instrument; differences in the number and intensity of fundamental/overtones.

14. Deafness
Conductive and Nerve
Temporary:
Wax, foreign obj, excess mucus, infection, drugs
Permanent:
Hereditary, genetic, prenatal exposure to disease, loud noise, trauma (ie: ruptured dear drum), diseases, exposure to chem, etc

15. Review Things, Lesson 3
Transmission – movement of sound waves through a medium
Absorption – transfer of energy by a wave to the medium through which it travels
Reflection – bouncing of a wave off of a surface

16. New Things 1, Lesson 3 Echo – reflected sound
Reverberation – collection of reflected sounds from the surfaces in a closed space
Acoustics – study of how sounds interact with structures
*Fun Fact*
Designing a space: Engineers design different rooms to reflect sound in different ways. The shape/contour of the walls and other structures in the room, as well as the materials they’re made of, reflect sound differently.
ie: a concert hall vs a classroom vs a recording studio

17. New Things 2, L3
Echolocation – use of reflected sounds to locate objects
Sound wave is sent out; some of the sound is reflected back
Sonar – Sound Navigation and Ranging – use of reflected sound waves to locate underwater objects
A sound wave is sent out into the water; as the sound wave goes deeper into the water, the wave spreads out in a cone/beam; when the wave strikes something, it is reflected back to the source of the wave

18. New Things 3, L3
Ultrasound – sounds that have a higher frequency than humans can hear (imaging, treatment)
Uses of ultrasound:
Imaging:
High-frq sound waves emitted; muscle, bone, tissue, fat, all reflect waves at different rates. Based on these reflections, and image can be created (sonogram)
Medical treatment:
Ultrasound therapy – high-frq sound waves emitted; the vibrations act like a massage for those muscles/tissues deeper in the body