Sound - The Nature of Sound Sound Waves Sound is a disturbance that travels through a medium as a longitudinal wave. As a gong vibrates, it creates sound

Sound - The Nature of Sound

Sound Waves

Sound is a disturbance that travels through a medium as a longitudinal wave. As a gong vibrates, it creates sound waves that travel through the air.

Sound - How You Hear Sound

The Human Ear

The outer ear funnels sound waves, the middle ear transmits the waves inward, and the inner ear transforms sound waves into a form that travels to your brain.

Sound - Music

Sound QualityThe sound quality of musical instruments results from blending a fundamental tone with its overtones. Resonance also plays a role in sound quality.


Interactions of Sound Waves

Sound waves reflect off objects, diffract through narrow openings and around barriers, and interfere with each other.


The Speed of Sound

The speed of sound depends on the elasticity, density, and temperature of the medium the sound travels trough.

Sound - Properties of Sound

Loudness

The loudness of different sounds is compared using a unit called the decibel (dB).


The Doppler Effect

The change in frequency of a wave as its source moves in relation to an observer is called the Doppler effect. When a sound source moves, the frequency of the waves changes because the motion of the source adds to the motion of the waves.


The Doppler Effect

When the plane travels almost as fast as the speed of sound, the sound waves pile up in front of the plane. This pile up is the “sound barrier.”

Sound12-8 Shock Waves and the Sonic Boom

Shock waves are analogous to the bow waves produced by a boat going faster than the wave speed in water.


When you sing, you change pitch using your vocal cords. Your vocal cords are located in your voice box, or larynx.

Changing Pitch

Sound - Using Sound

Echolocation

Some animals, including bats and dolphins, use echolocation to navigate and to find food.

Sound - Using Sound

Sonar

A sonar device sends out ultrasound waves and then detects the reflected waves.

Sound

Temperature and the Speed of Sound

The speed of sound in dry air changes as the temperature changes. The graph shows data for the speed of sound in air at temperatures from –10ºC to 20ºC.

- The Nature of Sound

Sound


The speed at –10ºC is325 m/s.

Reading Graphs:

What is the speed of sound in air at –10ºC?


Sound


The speed of sound increases as air temperature increases.

Interpreting Data:

Does the speed of sound increase or decrease as temperature increases?


Sound


At 30ºC, the speed of sound might be 349 m/s.

Predicting:

What might be the speed of sound at 30ºC?


Sound - Music

Groups of Musical Instruments

There are three basic groups of musical instruments: stringed instruments, wind instruments, and percussion instruments.


Elasticity

Elasticity is the ability of a material to bounce back after being disturbed. You can model elasticity by representing the particles in a medium as being held together by springs.


Density

Density is how much mass there is in a give volume. The volumes of the cubes are the same, but the brass has more mass.

Sound

Main Idea

Detail Detail Detail

Identifying Main IdeasAs you read the section “Interactions of Sound Waves,” write the main idea–the biggest or most important idea–in a graphic organizer like the one below. Then write three supporting details that further explain the main idea.

Sound waves interact with objects and with other sound waves.

Reflection occurs when sound waves strike a surface.

Sound waves can diffract around corners and through openings.

The interference of sound waves can be constructive or destructive.


Sound

Links on Sound

Click the SciLinks button for links on sound.


Sound

Speed of Sound

Click the Video button to watch a movie aboutthe speed of sound.


Sound

End of Section:The Nature of

Sound


Pitch

The pitch of a sound that you hear depends on the frequency of the sound wave.

Sound

OutliningAn outline shows the relationship between main ideas and supporting ideas. As you read, make an outline about the properties of sound. Use the red headings for the main ideas and the blue headings for the supporting ideas.

Properties of Sound

I. LoudnessA. Energy of a Sound

SourceB. Distance From a

Sound SourceC. Measuring Loudness

II. PitchA. Pitch and FrequencyB. Changing Pitch

III. Doppler EffectA. What Causes the

Doppler Effect?B. What Causes Shock

Waves?

- Properties of Sound

Sound

More on the Properties of Sound

Click the PHSchool.com button for an activityabout the properties of sound.


Sound

Pitch

Click the Video button to watch a movie about pitch.


Sound

End of Section:Properties of

Sound

Sound

Musical Instruments Activity

Click the Active Art button to open a browser window and access Active Art about musical instruments.

- Music

Sound

Previewing VisualsWhen you preview, you look ahead at the material to be read. Preview Figure 15. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions.

Musical Instruments

Q. How is pitch changed in each type of instrument?

A. By changing the frequency of the vibrations

Q. How is the loudness changed in each type of instrument?

A. By changing the energy of the vibrations

- Music

Sound

End of Section:Music

Sound

SequencingSequence is the order in which the steps in a process occur. As you read, make a flowchart that shows how you hear sound. Put the steps of the process in separate boxes in the order in which they occur.

How You Hear Sound

The outer ear funnels sound waves into the ear canal.

Sound waves make the eardrum vibrate.

Tiny bones in the middle ear transmit vibrations to the inner ear.

Vibrations in the cochlea of the inner ear send messages to the brain.

- How You Hear Sound

Sound

End of Section:How You Hear

Sound

Sound

Feature Echolocation Sonar

Comparing and ContrastingAs you read, compare and contrast echolocation and sonar by completing a table like the one below.

Type of wave Ultrasound Ultrasound

Medium(s) Air, water Water

Purposes Navigate, find foodFind water depth, sunken objects,schools of fish

- Using Sound

Using Sound

Sound

More on Sonar

Click the PHSchool.com button for an activity about sonar.

- Using Sound

Sound

End of Section:Using Sound

Sound

Graphic Organizer

Longitudinal waves

Sound

has properties

Intensity

Density Pitch

travels as

speed depends on is heard as is heard as

Frequency

Elasticity Temperature Loudness

Sound

End of Section:Graphic Organizer

Documents

Sound - The Nature of Sound Sound Waves Sound is a disturbance that travels through a medium as a longitudinal wave. As a gong vibrates, it creates sound