1. What is Sound and How is it Produced?
B. Davis and L. Blackburn
MathScience Innovation Center

2. Sound is vibrating matter.
If matter vibrates between
20 and 20,000 times in a second
humans hear it
Vibrating matter

3. Page 30 in notebook
Frequency is…
Number of times the vibrations complete a full cycle in one second
1 cycle per second= 1 hertz = 1 hz
Remember: Humans can hear 20-20,000 hz

4. Full cycle
Full to and fro movement
There and back
Complete vibration

5. How many full cycles?
2 cycles

6. If this lasts 6 seconds, find the frequency.
2 cycles in 6 seconds =
2/6 cycle per second
or 1/3 hertz (.33 hz)
Could a human hear this?

7. Sound is vibrating matter.
If it vibrates between
20 and 20,000 times in a second
humans hear it
Listen

8. Approximate Range (Hz)
Species
Approximate 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 
beluga whale
1, ,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
canary 
250-8,000 
parakeet 
200-8,500 
cockatiel
owl 
200-12,000 
chicken 
125-2,000 
Data source:

9. Graph source: http://encarta. msn

10. time to complete one full cycle.
Period is...
time to complete one full cycle.
If these 2 cycles occur in 6 seconds
What is the period?
3 seconds

11. Frequency =1/3 and period =3
Period - time for one complete cycle. Frequency- number of cycles per second. What is the relationship between period and frequency ?
Frequency =1/3 and period =3

12. What is the relationship between period and frequency ?
are reciprocals.
1/3 and 3

13. Period is how long one season lasts Frequency is how often they occur
Period is ¼ of a year
Frequency is 4 times per year

14. Find the frequency and period
Example: 60 vibrations are observed in 10 seconds.
Find the frequency and period
6 hz
1/6 sec
Could a human hear this?

15. Frequency is Pitch How can you make the sound pitch higher: On string?
On percussion?
On wind instrument?
HIGH
low

16. Frequency is Pitch
Listen to musical scale
HIGH
low

17. Loudness is Volume How can you make the sound louder: On string?
On percussion?
On wind instrument?
soft
LOUD

18. Loudness 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

19. Walkman at Maximum Level 100 dB Front Rows of Rock Concert 110 dB
Source
Intensity 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
Fact source:

20. Sound is caused by _________________ of matter
Recap:
vibrations
Sound is caused by _________________ of matter
The faster the vibration the higher the _________________________.
Frequency or pitch
Frequency is measured in _________________________.
Cycles per second or hertz (hz)

21. Recap: louder decibels (db)
The bigger the vibration the __________ the sound.
Loudness is measured in
_________________________.
decibels (db)