What is Sound What is Sound and and

How is it Produced?How is it Produced?

B. Davis and L. BlackburnB. Davis and L. BlackburnMathScience Innovation CenterMathScience Innovation Center

Sound is vibrating matter.Sound is vibrating matter.

If matter vibrates between If matter vibrates between

20 and 20,000 times in a second20 and 20,000 times in a second

humans hear ithumans hear it

Vibrating matterVibrating matter

Frequency is…Frequency is…

Number of times the vibrations complete a Number of times the vibrations complete a full cyclefull cycle in one second in one second

1 cycle per second= 1 hertz = 1 hz1 cycle per second= 1 hertz = 1 hz

Remember: Humans can hear 20-20,000 hz

Page 30 in notebook

Full cycleFull cycle

Full Full toto and and frofro movement movement There and backThere and back Complete vibrationComplete vibration

How many full cycles?How many full cycles?

2 cycles

If this lasts 6 seconds, find the If this lasts 6 seconds, find the frequency.frequency.

2 cycles in 6 seconds =

2/6 cycle per second

or 1/3 hertz (.33 hz)

Could a human hear this?

Sound is vibrating matter.Sound is vibrating matter.

If it vibrates between If it vibrates between

20 and 20,000 times in a second20 and 20,000 times in a second

humans hear ithumans hear it ListenListen

SpeciesApproximate Range (Hz) 

human 64-23,000

dog 67-45,000 

cat 45-64,000 

cow 23-35,000 

horse 55-33,500 

sheep 100-30,000 

rabbit 360-42,000 

rat 200-76,000 

mouse 1,000-91,000 

gerbil 100-60,000 

guinea pig 54-50,000 

hedgehog 250-45,000 

raccoon 100-40,000

ferret 16-44,000 

opossum 500-64,000 

chinchilla 90-22,800 

bat 2,000-110,000 

beluga whale 1,000-123,000

elephant 16-12,000 

porpoise 75-150,000

goldfish 20-3,000 

catfish  50-4,000 

tuna  50-1,100 

bullfrog  100-3,000 

tree frog 50-4,000 

canary  250-8,000 

parakeet  200-8,500 

cockatiel 250-8,000 

owl  200-12,000 

chicken  125-2,000 Data source: http://www.lsu.edu/deafness/HearingRange.html

Graph source: http://encarta.msn.com/media_461516319/Hearing_Range_in_Animals.html

Period is...Period is...

If these 2 cycles occur in 6 seconds

What is the period? 3 seconds

time to complete one full cycle.time to complete one full cycle.

PeriodPeriod - - time for one complete cycle.Frequency-Frequency- number of cycles per

second.What is the relationship between What is the relationship between

period and frequency ?period and frequency ?

Frequency =1/3 and period =3

What is the relationship between What is the relationship between period and frequency ?period and frequency ?

1/3 and 3

Period and frequencyPeriod and frequency are reciprocals.are reciprocals.

Period is how long Period is how long one season lasts one season lasts

Frequency is how Frequency is how often they occur often they occur

Period is ¼ of a year

Frequency is 4 times per year

Find the frequency and periodFind the frequency and period

1/6 sec

Example: 60 vibrations are observed in 10 seconds.

6 hz

Could a human hear this?

Frequency is PitchFrequency is Pitch

How can you make the sound How can you make the sound pitch higher:pitch higher:

On string?On string? On percussion?On percussion? On wind instrument?On wind instrument?

low

HIGH

Frequency is PitchFrequency is Pitch

low

HIGH

Listen to musical scaleListen to musical scale

Loudness is VolumeLoudness is Volume

How can you make the sound How can you make the sound louder:louder:

On string?On string? On percussion?On percussion? On wind instrument?On wind instrument?

soft LOUD

•measured in Decibels

•1 Bel = named after Alexander Graham Bell

•Decibel is 1/10 of a Bel

•Logarithmic Scale ( like earthquakes)

•A 30 dB sound is ten times louder than a 20 dB sound

•A 40 dB sound is one hundred times louder than a 20 dB sound

LoudnessLoudness

SourceIntensity Level

Threshold of Hearing 0 dB

Rustling Leaves 10 dB

Whisper 20 dB

Normal Conversation 60 dB

Busy Street Traffic 70 dB

Vacuum Cleaner 80 dB

Large Orchestra 98 dB

Walkman at Maximum Level 100 dB

Front Rows of Rock Concert 110 dB

Threshold of Pain 130 dB

Military Jet Takeoff 140 dB

Instant Perforation of Eardrum 160 dB

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Recap:Recap:

Sound is caused by _________________ Sound is caused by _________________ of matterof matter

vibrations

The faster the vibration the higher the _________________________.Frequency or pitch

Frequency is measured in _________________________.Cycles per second

or hertz (hz)

Recap:Recap:

The bigger the vibration the __________ the sound.

louder

Loudness is measured in

_________________________.decibels (db)