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