2 Review Terms Compression Rarefaction Longitudinal wave Medium WavelengthAmplitudeFrequencyInterference
3 New Things: Lesson 1 Sound wave: Vibration longitudinal wave Can only travel through matterVibrationRapid 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 mediumHow closely particles are packed togetherTemperature of the mediumInc temp = Inc speed of sound FOR GASESWhy? Inc in energy in particles = more energy transferredDec temp = Inc speed of sound FOR LIQ & SOLIDSWhy? 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 observerSource of sound is moving; observer is standing stillIntensity: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 seemsResonance: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 earMiddle EarAmplifies soundEardrum – sounds from outer ear cause eardrum to vibrate; vibrations transfer to 3 bones:HammerAnvilStirrupThese bones conduct sound towards inner ear
8 Detecting Sound 2 Inner Ear Turns sound waves into signals that can be recognized by the brainCochlea – small, fluid-filled chambersSound 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 ScaledBDescribes the intensity (loudness) of a sound
10 Relationship btwn vocab terms Frequency & wavelengthLonger wavelength = lower frequencyShorter wavelength = higher frequencyPitch & FrequencyHigher frequency = higher pitchLower frequency = lower pitch
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 vibratesOvertones – higher frequencies at which the material vibratesTimbre (TAM-bur) – caused by the interferences of these waves, unique to each instrument; differences in the number and intensity of fundamental/overtones.
14 DeafnessConductive and NerveTemporary:Wax, foreign obj, excess mucus, infection, drugsPermanent:Hereditary, genetic, prenatal exposure to disease, loud noise, trauma (ie: ruptured dear drum), diseases, exposure to chem, etc
15 Review Things, Lesson 3Transmission – movement of sound waves through a mediumAbsorption – transfer of energy by a wave to the medium through which it travelsReflection – 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 spaceAcoustics – 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, L3Echolocation – use of reflected sounds to locate objectsSound wave is sent out; some of the sound is reflected backSonar – 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
18 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