Sound Chp. 11 sect.1 The Nature of Sound

Sound  Sect. 1 The Nature of Sound slides 3-34  Sect. 2 Properties of Sound slides 35-56slides  Sect. 3 Music slides 57-72slides  Sect. 4 Using Sound slides 73-81slides 73-81

How Sound Travels  All sounds are made by something that vibrates.

How Sound Travels  All sounds are made by something that vibrates.  Sound waves are compressional Compression is close together Rarefaction is spread out molecules

How Sound Travels  All sounds are made by something that vibrates.  Sound waves are compressional Compression is close together Rarefaction is spread out molecules These areas alternate in a compressional wave.

How Sound Travels  Speakers vibrate outward forming compression  Speaker vibrates inward forming rarefaction

How Sound Travels  Speakers vibrate outward forming compression  Speaker vibrates inward forming rarefaction  Air molecules around speaker bump into other molecules; a series of compressions and rarefactions form a sound wave

What changes the speed of sound?  Depends on the material & whether it is solid, liquid or gas

What changes the speed of sound?  Depends on the material & whether it is solid, liquid or gas AirCORkCORk WATErWATEr BRICkBRICk A L U Min um 347 m/s 500 m/s 1498 m/s 3650 m/s 4877 m/s

What changes the speed of sound?  Depends on the material & whether it is solid, liquid or gas  Sound travels fastest through solids and slowest through gases. AirCORkCORk WATErWATEr BRICkBRICk A L U Min um 347 m/s 500 m/s 1498 m/s 3650 m/s 4877 m/s

What changes the speed of sound?  Depends on the material & whether it is solid, liquid or gas  Sound travels fastest through solids and slowest through gases.  When molecules are close, they transmit energy more quickly. AirCORkCORk WATErWATEr BRICkBRICk A L U Min um 347 m/s 500 m/s 1498 m/s 3650 m/s 4877 m/s

What changes the speed of sound?  Loud and soft sounds travel through a material at the same speed.

What changes the speed of sound?  Loud and soft sounds travel through a material at the same speed.  The closer the molecules are to each other, the faster they can transfer energy.

What changes the speed of sound?  Loud and soft sounds travel through a material at the same speed.  The closer the molecules are to each other, the faster they can transfer energy.  As temperatures increase, molecules move faster.

How your ears allow you to hear  Making sense of sound waves: 1) Ears gather compressional waves

How your ears allow you to hear  Making sense of sound waves: 1) Ears gather compressional waves 2) Amplify the waves

How your ears allow you to hear  Making sense of sound waves: 1) Ears gather compressional waves 2) Amplify the waves 3) Changed waves to nerve impulses

How your ears allow you to hear  Making sense of sound waves: 1) Ears gather compressional waves 2) Amplify the waves 3) Changed waves to nerve impulses 4) Brain translates nerve impulses

How does the outer ear gather waves?  Outside of ear with the ear canal and the eardrum make up the outer ear.

How does the outer ear gather waves?  Outside of ear with the ear canal and the eardrum make up the outer ear.  Eardrum is a tough membrane stretched over the end of the ear canal which vibrates when sound waves reach it.

What does the middle ear do?  Three tiny bones, hammer, anvil & stirrup make the vibrations stronger.

What does the middle ear do?  Three tiny bones, hammer-2, anvil-3 & stirrup-4 make the vibrations stronger.  This lever system makes the force & pressure of the sound waves stronger.

What does the middle ear do?  Three tiny bones, hammer, anvil & stirrup make the vibrations stronger.  This lever system makes the force & pressure of the sound waves stronger.  The stirrup connects to a membrane in the oval window which vibrates as the stirrup does.

What does the inner ear do?  Cochlea spiral- shaped structure, liquid-filled, contains tiny hair cells.

What does the inner ear do?  Cochlea spiral- shaped structure, liquid-filled, contains tiny hair cells.  When hair cells vibrate, nerve impulses are sent to brain

What does the inner ear do?  Cochlea spiral-shaped structure, liquid-filled, contains tiny hair cells.  When hair cells vibrate, nerve impulses are sent to brain  Cochlea changes sound waves to nerve impulses.

What does the inner ear do?  Cochlea spiral-shaped structure, liquid-filled, contains tiny hair cells.  When hair cells vibrate, nerve impulses are sent to brain  Cochlea changes sound waves to nerve impulses.  If hair cells are damaged or destroyed by loud sounds, person can lose ability to hear.

Object creates vibrations which are transferred through the air by Compressions To the outer ear, then transmitted through the Ear canal To the Where they are made stronger by the hammer And transmitted into the Where the Change them into brain waves

Object creates vibrations which are transferred through the air by Compressions To the outer ear, then transmitted through the Ear canal To the Where they are made stronger by the hammer And transmitted into the Where the Change them into brain waves Sound waves travel

Object creates vibrations which are transferred through the air by Compressions To the outer ear, then transmitted through the Ear canal To the Where they are made stronger by the hammer And transmitted into the Where the Change them into brain waves Sound waves travel Ear drum

Object creates vibrations which are transferred through the air by Compressions To the outer ear, then transmitted through the Ear canal To the Where they are made stronger by the hammer And transmitted into the Where the Change them into brain waves Sound waves travel Ear drum anvil

Object creates vibrations which are transferred through the air by Compressions To the outer ear, then transmitted through the Ear canal To the Where they are made stronger by the hammer And transmitted into the Where the Change them into brain waves Sound waves travel Ear drum anvilstirrup

Object creates vibrations which are transferred through the air by Compressions To the outer ear, then transmitted through the Ear canal To the Where they are made stronger by the hammer And transmitted into the Where the Changes them into brain waves Sound waves travel Ear drum anvilstirrup Inner ear

Object creates vibrations which are transferred through the air by Compressions To the outer ear, then transmitted through the Ear canal To the Where they are made stronger by the hammer And transmitted into the Where the Changes them into brain waves Sound waves travel Ear drum anvilstirrup Inner ear cochlea

Properties of Sound Sound Section 2

Properties of Sound  How amplitude, intensity, & loudness are related  How sound is measured  The relationship between frequency and pitch  The Doppler effect

How amplitude, intensity, & loudness are related  Intensity is the amount of energy that flows through a certain area in a specific amount of time.

How amplitude, intensity, & loudness are related  Intensity is the amount of energy that flows through a certain area in a specific amount of time.  Turning down volume reduces the energy carried by the sound waves and its intensity.

How amplitude, intensity, & loudness are related  Intensity affects how far a wave will travel.

How amplitude, intensity, & loudness are related  Intensity affects how far a wave will travel. Low intensity loses energy quickly High intensity travels farther

How amplitude, intensity, & loudness are related  Loudness is the way humans understand sound intensity. High intensity sounds make your eardrums vibrate further which in turn creates increased hair cell movements making you hear a loud sound instead of quiet one.

How is sound measured?  Loudness or intensity of sound is measured in decibels (dB).

How is sound measured?

The relationship between frequency and pitch  Pitch is how high or low a sound seems to be and is related to frequency of the sound waves.

The relationship between frequency and pitch  Frequency, measured in Hertz (Hz), refers to the number of wavelengths that pass by in 1 second.

The relationship between frequency and pitch  Frequency, measured in Hertz (Hz), refers to the number of wavelengths that pass by in 1 second. High frequency means many compressions hit your ear each second resulting in high pitch

The relationship between frequency and pitch  Frequency, measured in Hertz (Hz), refers to the number of wavelengths that pass by in 1 second. High frequency means many compressions hit your ear each second resulting in high pitch Low freq. mean low pitch, less compressions

Human hearing  A healthy human ear can hear sound waves from 20 to 20,000 Hz.

Human hearing  A healthy human ear can hear sound waves from 20 to 20,000 Hz.  Best hear sounds b/w 440 – 7,000 Hz

Human hearing  A healthy human ear can hear sound waves from 20 to 20,000 Hz.  Best hear sounds b/w 440 – 7,000 Hz  Ultrasonic frequencies above 20,000 Hz cannot be heard by humans. Dogs hear up to 35,000 Hz. Bats hear beyond 100,000 Hz.

Human hearing  A healthy human ear can hear sound waves from 20 to 20,000 Hz.  Best hear sounds b/w 440 – 7,000 Hz  Ultrasonic frequencies above 20,000 Hz cannot be heard by humans. Dogs hear up to 35,000 Hz. Bats hear beyond 100,000 Hz.  Infrasonic or subsonic waves have freq. below 20 Hz like wind, heavy machinery, earthquakes…can be felt not heard

Doppler Effect  Change in pitch or frequency because a wave source is moving.

Doppler Effect  It is also noticeable when you are moving past a sound source that is standing still.  The faster the change in position, the greater the change in frequency & pitch.

How is the Doppler Effect used?  Radar guns measure speed of cars  Weather radar tracks wind in storms

Intensity, high-amplitude, ultrasonic, decibel, subsonic, freq.  ____ sound frequencies are too high for humans to hear. As the ___ of a sound wave increases, the pitch increases. In a ___ sound wave, the compressions are dense. The ___ is the unit for measuring how intense a sound is. As the ___ of a sound wave increases, the loudness increases. Another name for infrasonic is ___.

Intensity, high-amplitude, ultrasonic, decibel, subsonic, freq.  Ultrasonic sound frequencies are too high for humans to hear. As the frequency of a sound wave increases, the pitch increases. In a high-amplitude sound wave, the compressions are dense. The decibel is the unit for measuring how intense a sound is. As the intensity of a sound wave increases, the loudness increases. Another name for infrasonic is subsonic.

Music Sound section 3

Music  The difference between noise & music  Why different kinds of instruments sound differently  How instruments make music  How beats are made

Music  Noise has random patterns and pitches.  Music is made up of sounds that are carefully chosen and have regular patterns.

Natural frequencies  Every material will vibrate at its natural frequencies dependent upon: Thickness Length Tightness

Every musical instrument…  Contains something that vibrates at its natural frequencies to create a pitch. Strings- guitar, violin Membrane- drum column of air- flute, oboe

Resonance  The ability of a medium to vibrate by absorbing energy at its own natural frequency.  Resonance helps amplify the sound of many musical instruments.

Sound Quality  Describes the differences among sounds of the same pitch and loudness.  Each instrument has its own sound quality.  Main tone that is played & heard is called the fundamental frequency.

Overtones  Vibration with a frequency that is a multiple of the fundamental.

Overtones  Suppose a guitar vibrates at a fundamental frequency of 250 Hz. Multiples of 250 are 500 Hz, 750 Hz, 1000 Hz and so on.  Overtones create the rich sounds of a guitar.  Every instrument has a different number & intensity of overtones.

How do string instruments produce sound?  Plucking, striking, or moving a bow across a string produces sound.

How do string instruments produce sound?  Plucking, striking, or moving a bow across a string produces sound.  A resonator is a hollow space filled with air that makes sound louder when the air inside it vibrates.

How do string instruments produce sound?  Plucking, striking, or moving a bow across a string produces sound.  A resonator is a hollow space filled with air that makes sound louder when the air inside it vibrates.  Ex. Violins, electric guitars, harps

What about brass & woodwinds?  Brass have a cone-shaped mouthpiece inserted in a metal tube resonator which produces a pitch

How do percussion instruments make sound? They are hit, shaken or rubbed to produce sound.

Musical Instruments String instruments Wind instruments Percussion instruments cymbal flute Electric guitar

Musical Instruments String instruments Wind instruments Percussion instruments cymbal flute Electric guitaroboe horn trombone violin harp cello Steel drums xylophone Bass drum

Using sound Sound Section 4

What You’ll Learn  What affects sound in a concert hall  How some animals use sound waves  How sonar is used  About ultrasound

What affects sound in a concert hall  Reverberation is the echoing produced by many reflections of sound that make it difficult to hear clearly.  Acoustics is the study of sound.  Soft materials like carpet and drapes can reduce reverberations.

Echolocation  Process of locating objects by making sounds and interpreting the sound waves that reflect or bounce back

Sonar  A system that uses reflections of underwater sound waves to detect objects.

Sonar  A system that uses reflections of underwater sound waves to detect objects.  A hydrophone picks up the reflected sound. Since the speed of sound in water is known, the distance can be found by measuring time.

Ultrasonic waves  Can also be used to clean delicate items like jewelry

Ultrasonic waves  Can also be used to clean delicate items like jewelry  Can be used to make images of soft body parts without doing surgery

Ultrasonic waves  Can also be used to clean delicate items like jewelry  Can be used to make images of soft body parts without doing surgery  Kidney stones and gallstones can be broken up with ultrasound treatments