Unit: Sound and Light Lesson 2 Properties of Sound Essential Questions: 1.) What affects pitch? 2.) What affects loudness? 3.) What causes the Doppler Effect?

How high or lowPitch the sound seems What Affects Pitch? Low pitchHigh pitch

When your vocal cords stretch, they vibrate more quickly. This creates a higher frequency and higher pitch. When your vocal cords relax, they vibrate lower frequency sound waves with lower pitches.

Awareness of the Loudness energy of sound Loudness depends on: 1.) Energy- the more energy the louder the sound 2.) Intensity- the closer to the source, the louder it sounds What Affects Loudness?

When you hit a drum harder, you transfer more energy to it. It sounds louder. If you move closer to the stage, the music sounds louder. The sound wave has a smaller area to cover.

The Doppler Effect Have you ever listened to the siren of a police car. Why do you think the pitch of the siren changes when the police car goes by?

The change in frequencyDoppler Effect of a wave as its source moves High Pitch Low Pitch

How high or lowPitch the sound seems What Affects Pitch? Low pitchHigh pitch

The frequency of a wave is affected by how fast the medium is vibrating With glasses, the frequency is how fast the air is vibrating.