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Flashcards in Sound Deck (28)
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1

What are the two things that must be present in the production of sound?

Something that vibrates
Something that Resonates

2

Number of waves per second

Frequency (measured in Hz)

3

Frequency is perceived subjectively as what?

Pitch

4

The lower the pitch, the lower the ______________?

Frequency

5

A lower pitch has a ________(longer, shorter) wave.

Longer

6

Speed of Sound in AIR

340 m/sec

7

What is the human range for frequency?

20-20,000 Hz

8

Below 20 Hz

infrasonic

9

Above 20,000 Hz

ultrasonic

10

Measurement unit for loudness

Decibels (dB)

11

Practical range for loudness (humans)

0 dB to 120 dB

12

If the decibel level is 10 times greater, the sound is _____ as loud.

Twice.

13

What type of wave is sound?

Longitudinal

14

Why is it silent in outer space?

There is not medium (no air) for sound to travel in.

15

A vibrating object forces a second object to vibrate

Forced vibration

16

An object with elasticity will vibrate at its own frequency. This is the object's ___________________.

Natural Frequency

17

This happens when forced vibrations take place at the natural frequency, creating a peak of energy

Resonance

18

What happens when two identical waves come together and are out of phase?

The sound becomes muted or muffled.

19

What happens when two identical waves come together and are in phase?

The amplitude of the wave is increased and the sound becomes louder.

20

The difference in two sounded frequencies is called what?

The Beat Frequency

21

If two tones of slightly different frequencies are sounded together, what happens to the sound?

There is a periodic variation in the loudness of the sound.

22

A periodic variation in the loudness of sound

Beats

23

Doppler Effect

An apparent shift in frequency due to the motion of a source, an observer or both

24

With the Doppler Effect, the wavelength is _____________ as a source approaches, making the frequency __________________.

Shortened; Higher

25

With the /Doppler Effect, the wavelength is ______________ as a source leaves, making the frequency ___________.

Lengthened; Lower

26

Doppler Effect can occur with ___________ or _____________.

Sound; Light

27

If objects move away from an observer, there is a ______________ frequency or a _____ shift.

Lower; Red

28

If objects move towards the observer, there is a _______________ frequency or a ________ shift.

Higher; Blue