OK everyone get ready to learn a new vocabulary term.

Pitch Today we are going to learn about pitch.

Doppler Effect The Doppler effect,

Interference interference,

Resonance And resonance.

Before we define these terms, let’s review some other words that you already learned, and make sure you are firm in your understanding.

sound waves Sound waves are longitudinal waves that travel through a medium.

medium A medium is any material that waves can travel through.

vibration Vibration is the movement of particles that occurs in solids, liquids, or gases.

compression Compression is the area in a longitudinal wave where particles are closest together.

rarefaction Rarefaction is the area in a longitudinal wave where the particles are furthest apart.

frequency Frequency is the number of wavelengths that pass a set point, per second.

Now let’s pause for a moment to review the information we have covered already.

What is a sound wave?

What sections are seen in a sound wave? Rarefaction and compression

What is frequency? Frequency is the number of wavelengths that pass a set point, per second.

Pitch First we are going to look at pitch.

pitch Let’s define what pitch is.

pitch: the perception of how high or low a sound seems. A sound’s pitch is how low or high it seems to be when you hear it.

High Frequency = High Pitch The higher the frequency, the higher the pitch.

Doppler Effect Now let’s define what the Doppler Effect is.

Doppler Effect: the change of pitch you hear when a sound source is moving closer and further away from you The Doppler effect is the change of pitch you hear when a sound source is moving closer and further away from you.

If you are standing near the train, the whistle sounds high.

But after the train passes you, the whistle’s pitch drops and it sounds low.

Doppler Effect The pitch of the whistle is dependent on the train’s location relative to you.

Now let’s pause for a moment to review the information we have covered already.

What is pitch? A sound’s pitch is how low or high it seems to be when you hear it.

What change is the a scientist observing as a result of the Doppler Effect? The Doppler effect is the change of pitch you hear when a sound source is moving closer and further away from you.

True or False: The Doppler Effect is created because the initial vibration changed. False.

interference Next, let’s define interference.

interference: occurs when waves overlap, combine, and form a new wave

Interference Constructive Destructive There are two types of intereference.

Constructive Interference Constructive Interference occurs when 2 compressions from 2 different sound waves meet and combine to form a new wave with higher intensity and a larger amplitude.

Destructive Interference Destructive interference occurs when a compression and a rarefaction from difference waves combine to create a less intense and smaller amplitude wave.

This is how noise canceling headphone work This is how noise canceling headphone work. They create destructive interference by creating a wave that is exactly opposite of the sound from the environment.

resonance Next, let’s define resonance.

resonance: occurs when an object absorbs sound energy from another object vibrating at the same frequency Resonance occurs when an object absorbs sound energy from another object vibrating at the same frequency.

resonance = larger amplitude + 6 KHz 6 KHz When resonance occurs, the amplitude of the new wave is larger than the amplitude of the separate objects’ wavelengths. resonance = larger amplitude

Now we are going to look at an example of resonance.

Guitar When the guitar string vibrates,

Guitar The air inside the guitar vibrates by resonance.

Increasing amplitude Amplifying the sound of the string.

Now let’s review all the information we have covered today.

What is resonance?

Which is affected by the location of a sound’s source? Doppler Effect Vibration Resonance Medium

Which is affected by the location of a sound’s source? Doppler Effect Vibration Resonance Medium

Which type of interference creates waves with large amplitudes? Deletion Destructive Constructive Completion The distance between to like points.

Which type of interference creates waves with large amplitudes? Deletion Destructive Constructive Completion The distance between to like points.

Which type of interference creates waves with decreased intensity? Deletion Destructive Constructive Completion The distance between to like points.

Which type of interference creates waves with decreased intensity? Deletion Destructive Constructive Completion The distance between to like points.

What occurs when waves overlap and create new waves? interference

Remember!!! So remember! <keep this slide>

pitch: the perception of how high or low a sound seems. A sound’s pitch is how low or high it seems to be when you hear it.

Doppler Effect: the change of pitch you hear when a sound source is moving closer and further away from you The Doppler effect is the change of pitch you hear when a sound source is moving closer and further away from you.

interference: occurs when waves overlap, combine, and form a new wave

resonance: occurs when an object absorbs sound energy from another object vibrating at the same frequency Resonance occurs when an object absorbs sound energy from another object vibrating at the same frequency.

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Questions or Comments to Michael Kennedy, Ph.D. This Video Created With Resources From: Cooperative Agreement # R324B130023 Curry School Foundation’s Research and Development Fund Questions or Comments to Michael Kennedy, Ph.D. MKennedy@Virginia.edu

Activity Objective: Students will understand the relationship between frequency and pitch. Activity: Student will work through 2 lab stations. The first will allow them to look at how the length of a ruler affects the pitch and frequency the sound makes. The second will allow the student to make “kazoos” and see how they can change the pitch. Materials: Ruler Plastic straw Scissors worksheet Resources: https://www.teachengineering.org/activities/view/cub_energy2_lesson05_activity3