1. Sound

2. Characteristics of Sound Lab
Demo with keyboard
Program

3. If a tree falls in the woods and there is no one there to hear it, does it make a sound?

4. The Sonic Spectrum – all mechanical, longitudinal waves.

5. RAP

6. Sound Ranges Infrasonic – less than 20 Hz
Ultrasonic – more than 20,000 Hz
Range of Human Hearing
20 – 20,000 Hz
0 – 120 dB

8. Driver Type Minimum Frequency Maximum Frequency Subwoofer < 20Hz
300-3kHz
Mid Woofer
3kHz
Midrange
300Hz
Tweeter
1.5kHz
> 20kHz
Super Tweeter
10kHz
30kHz
Typical Loudspeaker Driver Ranges

9. 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 
opossum
500-64,000 
guinea pig
54-50,000 
hedgehog
250-45,000 
raccoon
100-40,000
ferret
16-44,000 
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 

10. What do these sound like?
We hear from Hz.
Will 2000 Hz sound “high” or “low” pitched?

11. Speed of Sound Distance and time Wavelength and frequency
Characteristics of the material the sound is traveling in

12. Speed of Sound in Air Sound Travels Faster in Hotter Air

13. At 25°C

14. At -25°C

15. Ear Diagram
Use the diagram that I pass out to you record the function for important parts of the ear.
Test questions require that you match important structures with their function.
You will not have to label or identify structures on a diagram.

17. Size of the ossicles

18. Size of the cochlea

19. “tubes”

20. Decibels – a measure of the relative intensity of sounds.

21. Normal Conversation – 60 dB

22. 85 decibels - prolonged exposure can cause gradual hearing loss
85 decibels - prolonged exposure can cause gradual hearing loss. 100 decibels - no more than 15 minutes prolonged exposure recommended 110 decibels - regular exposure of more than one minute risks permanent hearing loss without hearing protection.  

23. Loudest Sounds Ever! dragster 155-160
400,000 Watt speakers decibel
fireworks
dragster
Space shuttle
blue whale 188
The Tunguska event 315 June 30, 1908

24. Important Decibel Ideas
This is a “relative” (comparing) scale.
Humans can distinguish about 1 dB.
10dB higher “sounds” 2x louder.
Logarithmic, not linear.
10x more energy = 10dB higher
100x more energy = 20dB higher
1000x more energy = 30dB higher
10,000,000x more energy = 70dB higher

25. Bettendorf – measured 4 ft above the ground at property line
Residential
(7am-10pm) 60dB
(10pm-7am) 50dB
No lawn mower, trimmer chain saws
Commercial (all times) 65dB
Industrial (all times) 75 dB

26. Beats

27. Two similar sounds played together

28. Sonometer

29. Sound Frequency = Average Beat Frequency = Difference