Chapter 11. Review Terms Compression Rarefaction Longitudinal wave Medium Wavelength Amplitude...
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Transcript of Chapter 11. Review Terms Compression Rarefaction Longitudinal wave Medium Wavelength Amplitude...
SOUNDChapter 11
Review TermsCompressionRarefactionLongitudinal waveMediumWavelengthAmplitudeFrequencyInterference
New Things: Lesson 1Sound wave:
longitudinal waveCan only travel through matter
VibrationRapid 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
What Affects the Speed of Sound?1) Density/stiffness of the medium
How closely particles are packed togetherTemperature of the medium
Inc temp = Inc speed of sound FOR GASES Why? Inc in energy in particles = more energy
transferredDec temp = Inc speed of sound FOR LIQ &
SOLIDS Why? Dec in temp = particles closer together =
faster for sound to travel throughout the medium
New Things, Lesson 2Doppler effect:
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
More New Things: Lesson 2Pitch:
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)
Detecting Sound 1Outer Ear
Collects soundEar canal – directs collected sounds to middle ear
Middle EarAmplifies soundEardrum – sounds from outer ear cause eardrum
to vibrate; vibrations transfer to 3 bones: Hammer Anvil Stirrup
These bones conduct sound towards inner ear
Detecting Sound 2Inner Ear
Turns sound waves into signals that can be recognized by the brain
Cochlea – small, fluid-filled chambers1. Sound passing through cochlea causes tiny
hair-like cells to vibrate;2. movement of these cells produces nerve
signals;3. signals travel to brain;4. signals interpreted as sound.
Decibel ScaledBDescribes the intensity (loudness) of a sound
Relationship btwn vocab termsFrequency & wavelength
Longer wavelength = lower frequencyShorter wavelength = higher frequency
Pitch & FrequencyHigher frequency = higher pitchLower frequency = lower pitch
Sound InterferenceConstructiveDestructiveBeats
BeatsHow to calculate beats:
The difference in frequenciesie: 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
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.
Fundamental & Overtones
Deafnesshttp://www.betterhealth.vic.gov.au/bhcv2/bhc
articles.nsf/pages/Deafness_-_a_range_of_causes
Conductive and NerveTemporary:
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
Review Things, Lesson 3Transmission – 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
New Things 1, Lesson 3Echo – 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
New Things 2, L3Echolocation – use of reflected sounds to locate
objectsSound wave is sent out; some of the sound is reflected
back
Sonar – Sound Navigation and Ranging – use of reflected sound waves to locate underwater objectsA 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
New Things 3, L3Ultrasound – 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