Sound waves are the same as the physical waves we already learned about, but there's a lot to talk about so they get their own lesson. You can think of sound waves as a traveling wave of air pressure, while the individual air molecules themselves only oscillate back and forth and don't travel with the wave. When an instrument or a speaker oscillates and produces sound waves, the wave travels to your eardrum. Your eardrum oscillates at the same frequency, allowing you to hear the sound.

Have you ever noticed that when a police car, ambulance, or race car drives by you the pitch of their siren or engine seems to get lower? That's the doppler effect in action. We'll learn how a moving sound source or observer actually changes the wavelength, frequency and pitch of sound waves.

We'll also cover how sound waves interfere with each other the and interesting effects that produces.

• Flipping Physics - What is Sound?
• Khan Academy - Beat frequency
• Flipping Physics - Doppler Effect Demonstrations and Animations
• Khan Academy - Doppler effect formula for observed frequency
• Khan Academy - Doppler effect formula when source is moving away

• Organic Chemistry Tutor - Sound Waves, Intensity, Beat Frequency, Doppler Effect

• Sound Waves in Action

• Standing Waves
• Doppler Effect
• Superposition and Standing Waves
• Longitudinal and Transverse Waves
• Beat Frequency

Other Resources

Sound waves are the same as the physical waves we already learned about, but there's a lot to talk about so they get their own lesson. You can think of sound waves as a traveling wave of air pressure, while the individual air molecules themselves only oscillate back and forth and don't travel with the wave. When an instrument or a speaker oscillates and produces sound waves, the wave travels to your eardrum. Your eardrum oscillates at the same frequency, allowing you to hear the sound.

Have you ever noticed that when a police car, ambulance, or race car drives by you the pitch of their siren or engine seems to get lower? That's the doppler effect in action. We'll learn how a moving sound source or observer actually changes the wavelength, frequency and pitch of sound waves.

We'll also cover how sound waves interfere with each other the and interesting effects that produces.