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Sound What causes sound? vibrations of molecules.

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Presentation on theme: "Sound What causes sound? vibrations of molecules."— Presentation transcript:

1 Sound

2 Sound What causes sound? vibrations of molecules

3 Sound Waves Sound Waves: compressional waves that are produced when vibrations from an object collide with molecules

4 Sound waves Can travel through solids, liquids and gases but not empty space

5 Speed of Sound Depends on.........
1.  The type of medium (gas, liquid or solid) travels fastest in solids 2. The temperature of the medium- travels through warm mediums faster

6 How we hear sound… 1. The outer ear gathers sound waves
2.  The middle ear amplifies the sound waves 3.  The inner ear converts the sound waves to nerve impulses 4.  The nerve impulses travel to the brain to be decoded and interpreted



9 How we hear sound Eardrum: a tough membrane in the ear that vibrates when sound enters it Cochlea: a spiral-shaped, fluid filled cavity in the inner ear that vibrates and sends nerve impulses to the brain

10 Properties of Sound Intensity: the amount of energy that flows through a certain area in a specific amount of time High intensity = high energy Loudness: the human perception of sound intensity

11 Properties of Sound Decibel (dB): a unit on the scale of sound intensity 0 dB is the faintest sound humans can hear 120 dB main cause pain and damage to ears



14 Pitch Pitch: how high or low a sound is
Frequency and pitch: the higher the frequency the higher the pitch

15 Ultrasonic vs. infrasonic waves
Ultrasonic waves: frequencies above 20,000 Hz Infrasonic waves: frequencies below 20 Hz Humans: can hear frequencies between 20 and 20,000 Hz


17 1. Which 2 animals have the largest hearing range. ______________ 2
1.  Which 2 animals have the largest hearing range? ______________ 2.  Which animal can hear the highest frequency sounds? ______ 3.  What range of hearing does a fish have? __________ 4.  Which animal has the smallest range of hearing? _______ 5.  The range of a rodent's hearing is similar to that of a __________

18 What is the dB of a baby crying. What is the Hz of a baby crying
What is the dB of a baby crying? What is the Hz of a baby crying? What is the dB of an airplane? What is the Hz of an airplane? What is the dB of birds? What is the Hz of birds?

19 Sonic Boom

20 Moving sound Doppler effect: a change in the pitch of a sound wave due to the source of the sound moving Toward: when the object is moving toward the observer, the pitch is higher Away: when the object is moving away form the observer, the pitch is lower

21 The Doppler Effect

22 Using Sound Sonar: a system that uses the reflection of underwater sound waves to detect objects Equation: d = st/2 guide-to-submarines-sonar-video.htm

23 Using Sound Echolocation: animals using sonar to locate prey

24 Using Sound Ultrasound imaging: uses sound waves to produce images of internal body structures

25 Music Music: sounds produced in a deliberate pattern
Instruments produce sound in different frequencies Natural Frequencies: every material or object has a natural frequency at which it vibrates Frequencies of guitar strings depend on thickness, length and how tightly it's stretched.

26 Music Sound Quality: describes differences among sounds of the same pitch and loudness Each instrument has its own unique sound quality

27 Music Resonance and music: the sound of music is amplified by the resonance of instruments

28 Types of instruments Strings: violin, cello, guitar
Produce notes and the hollow chamber is the resonator (amplifier) Stretching the sting changes the pitch

29 Types of instruments 2. Brass and woodwinds: flute, trumpet, clarinet
Air is blown through a reed an the air resonates in the chamber (amplifier) Most are wood but can be brass or other metals

30 Types of instruments 3. percussion: drums, xylophone, triangle
Resonance happens in a chamber (amplifier) feature=related

31 Beats Beat: occur when sound waves of almost the same frequencies interfere with each other forming a standing wave Acoustics: the study of sound Uses reflection and absorption of sound waves to design concert halls and auditoriums




35 1. Sound travels faster in [ warm / cold ] air.
 2.  The bones of the middle ear serve to ______________ the sound. 3.  Sound moves through air by colliding with                                              [ molecules / energy ].     4.  Sound moving through air is a                   [ transverse / compressional ] wave. 5. Sound intensity is measured in ____________ 6.  Sounds waves with frequencies below 20 Hz are called [ ultrasonic / subsonic ] 7.  Name an organism that uses echolocation: ___________ 8. What is the job of the outer ear? zx9. What is the study of sound called? 10.  Give one example of a percussion instrument.

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