Chapter 9.2 - What is Sound

Question 1

What creates sounds?

Answer 1

Sounds are created by objects vibrating.

Question 2

What do vibrations of an object cause in the medium?

Answer 2

This vibration causes pressure changes in the medium, creating waves similar to waves on a pond.

Question 3

How do sound waves and pond waves behave as they spread out?

Answer 3

The waves of sound and pond waves do not change as they spread out. The initial pressure change is dispersed over a larger area as the sound wave moves away from its source.

Question 4

How does the speed of sound waves compare to light waves in different substances?

Answer 4

Sound waves travel faster through denser substances. Light waves move through air faster than sound waves do, which is why we see lightning before we hear thunder.

Question 5

What can sound waves be described as?

Answer 5

Fluctuations in air pressure across time

Question 6

Amplitude/Intensity (loudness)

Answer 6

Difference between the highest pressure and lowest pressure of a wave.

Question 7

What is Frequency (pitch)? Rate of fluctuation

Answer 7

Number of times per second that a pattern of pressure change repeats, determines how high or low a sound is

Question 8

How do larger and smaller animals differ in their ability to hear different frequencies?

Answer 8

Larger animals are better at hearing low frequencies, while smaller animals are better at using high frequencies.

Question 9

What is a Hertz (Hz)?

Answer 9

A unit of measure for frequency, where 1 hertz equals 1 cycle per second.

Question 10

What are Decibels (dB)?

Answer 10

Unit of measure for the physical intensity of sound. When comparing two sound pressures, the ratio between them can be expressed in decibels.

Question 11

What is the significance of small changes in decibels?

Answer 11

Relatively small changes in decibels can correspond to large physical changes in sound intensity.

Question 12

What is a Sine wave?

Answer 12

A smooth, repetitive oscillation that moves up and down in a wave-like pattern. also known as a pure tone

Question 13

What is a Pure tone?

Answer 13

Simple and smooth sound that goes up and down in a regular way. It is often referred to as a single frequency sine wave.

Question 14

Spectrum

Answer 14

Displays how much energy, or amplitude is present at multiple frequneices

Question 15

What are Harmonic Spectra?

Answer 15

Refers to a collection of frequencies present in a signal or waveform,

Question 16

Fundamental Frequency

Answer 16

The first harmonic is called the fundamental frequency, which is the lowest and most basic pitch that can be heard in a sound.

Question 17

Why do harmonic sounds with the same fundamental frequency sound different?

Answer 17

Harmonic sounds with the same fundamental frequency can sound different because the amplitudes of individual frequency components are different, resulting in different spectral shapes.

Question 18

Timbre

Answer 18

The “texture” or sensation we use to discriminate between two sounds
that have the same pitch and loudness.