1. C Sound
Physics 1

2. 15.1 Properties of Sound
If you could see atoms, the difference between __________________is not as great.
The image below is exaggerated to show effect.

3. The frequency of sound
We hear __________________as having different pitch.
A ________________sound has a low pitch, like the rumble of a big truck.
A _________________ sound has a high pitch, like a whistle or siren.
In speech, women have ________ ____________________ than men.

4. Complex sound
When we hear complex sounds, the nerves in the ear respond separately to each
different frequency. The brain interprets the signals from the ear and creates a
“sonic image” from the frequencies. The meaning in different sounds is derived
from the patterns in how the different frequencies get louder and softer. 4

5. Common Sounds and their Loudness

6. Loudness
Logarithmic scale
Linear scale
Decibels (dB)
Amplitude 1 20 10 40
100 60
1,000 80
10,000
100,000
120
1,000,000
Every _______________, means the pressure wave is ____________ ___________________.

7. Sensitivity of the ear
How we hear the loudness of sound is affected by the __________ of the sound as well as by the __________
The human ear is _________ ___________ to sounds between 300 and 3,000 Hz.
The ear is less sensitive to sounds outside this range.
Most of the ____________ that make up _________are between ________________Hz.
The Equal Loudness Curve on the right shows how sounds of different frequencies
compare. Sounds near 2,000 Hz seem louder than sounds of other frequencies, even at the same
decibel level.
For example, the Equal Loudness Curve shows that a 40 dB sound at 2,000 Hz
sounds just as loud as an 80 dB sound at 50 Hz. 7

8. How sound is created
The human voice is a complex sound that starts in the _______, a small structure at the top of your windpipe.
The sound that starts in the larynx is ___________________ ____________in the throat and mouth.
Different sounds are made by changing both the vibrations in the larynx and the shape of the openings.
The Equal Loudness Curve on the right shows how sounds of different frequencies
compare. Sounds near 2,000 Hz seem louder than sounds of other frequencies, even at the same
decibel level.
For example, the Equal Loudness Curve shows that a 40 dB sound at 2,000 Hz
sounds just as loud as an 80 dB sound at 50 Hz. 8

9. How sound is created
A _____________ is a device that is specially designed to __________ ___________________
The working parts of a typical speaker include a ___________, a coil of _______, and a _______.

10. Recording sound
A common way to record sound starts with a ______________.
The microphone transforms a ___________________ ____________with the same pattern of oscillation.
In modern digital recording, a sensitive circuit converts ________________________values between 0 and 65,536.

11. Recording sound
______________ correspond to the amplitude of the signal and are _________________. ______________ __________________________ is a list of 44,100 numbers.

12. Recording sound
To play the sound back, ______________________is read by a laser and converted into ____________ signals again by a second circuit which ________ the process of the previous circuit.

13. Recording sound
The electrical signal is ___________ until it is powerful enough to _________________________and reproduce the sound.

14. Sound Waves We know sound is a wave because:
Sound has both ___________and _________.
The ___________________is frequency times wavelength.
Resonance happens with sound.
Sound can be ___________, ___________ and ____________ and also shows evidence of ____________ and ________________.

15. Sound Waves
A ________________ is a wave of alternating high-pressure and low-pressure regions of air.

16. Amplitude of sound The amplitude of a sound wave is very small.
Even a loud 80 dB noise creates a ___________ ______________of only a few millionths of an atmosphere.

17. The wavelength of sound

18. The Doppler effect
The ________________________________ is called the Doppler effect.
It occurs when _____________________________less than the speed of sound.

19. The speed of sound
The speed of sound in air is _________________ (660 miles per hour) at one atmosphere of pressure and room temperature (21°C).
An object is ____________ when it is moving slower than sound.

20. The speed of sound
We use the term ________________to describe motion at speeds _________than the speed of sound.
A shock wave forms where the _________________.
The pressure change across the shock wave is what causes a very loud sound known as a ____________.

21. The speed of sound
The speed of a sound wave in air _________________ _________________ _________________.
The speed of sound in materials is often ____________ than in air.

22. Standing waves and resonance
Spaces enclosed by boundaries can create ______________ with sound waves.
The___________end of a pipe is a closed boundary.
An open boundary makes ________________ in the standing wave.
Sounds of different frequencies are made by _____________________________.
A particular sound is selected by designing the length of a vibrating system to be resonant at the desired frequency.

24. Sound waves and boundaries
Like other waves, sound waves can be ___________________ ______________as they pass from one material to another.
Sound waves reflect from ______ surfaces.
Soft materials can _________sound waves.

25. Fourier's theorem
Fourier’s theorem says any complex wave can be made from a _________ _______________ ______________ waves.

26. Sound spectrum
A complex wave is really a sum of component frequencies.
A frequency spectrum is a graph that shows the amplitude of each component frequency in a complex wave.

27. Sound, Perception, and Music
A single frequency by itself does not have much meaning.
The meaning comes from patterns in many frequencies together.
A sonogram is a special kind of graph that shows how loud sound is at different frequencies.
Every person’s sonogram is different, even when saying the same word.

28. Patterns of frequency
The brighter the sonogram, the ___________ the sound is at that ___________.

29. Hearing sound
The ________ vibrates in response to sound waves in the _________.
The three delicate bones of the inner ear _________ ____________ of the eardrum to the side of the cochlea.
The _______ in the spiral of the cochlea __________ _______________that travel up the spiral.

30. Sound
The nerves near the beginning see a relatively ________ __________ and respond to longer wavelength, low frequency sound.
The nerves at the __________________ of the channel respond to shorter wavelength, higher-frequency sound.

31. Music
The pitch of a sound is _____________________ its frequency. Though pitch and frequency usually mean the same thing, the way we hear a pitch can be _______________________________ ____________________________
Rhythm is a regular time pattern in a sound.
Music is a _____________________________ that we find pleasant.
Most of the music you listen to is created from a pattern of _________________________________.

33. Consonance, dissonance, and beats
__________________ is the study of how sounds work together to create effects desired by the composer.
When we hear more than one frequency of sound and the combination sounds good, we call it _________________.
When the combination ________________or unsettling, we call it dissonance.

34. Consonance, dissonance, and beats
Consonance and dissonance are related to beats.
When frequencies are far enough apart that there are no beats, we get consonance.
When frequencies are ________________, we hear beats that are the cause of dissonance.
Beats occur when _____________________, but not exactly the same.

36. Harmonics and instruments
The ______________sounds different when played on different instruments because the sound from an instrument is not a _______________________.
The variation comes from the ________________, _________________ of the fundamental note.