I. What is Sound? Longitudinal waves or compression waves. Created by vibrations Vibrations are composed of Compression Rarefaction Medium (or media) Substance through which a wave can travel Such as air. Vacuum = no air = no sound Sound waves travel in all directions away from their source. II. Properties of Sound Speed of Sound 343 m/s at 20 degrees Celsius Air What is it affected by? Medium: Travels faster in liquids Even faster in solids Temperature Travels faster at higher temperatures MaterialTypical velocity (m/s) Air (0C)331 Air (20C)344 Water (25C)1498 Pine3300 Glass 5000 Steel5000 Granite6000 Table of Velocity of sound III. Pitch and Frequency Pitch How high or low a sound seems to be Related to frequency High frequency = high pitch Low frequency = low pitch Measured in: Hertz (Hz) 1 Hz = 1 wave per second Examples Lowest note on a piano is 40 Hz Screech of a bat is 10,000 Hz IV. Loudness and Amplitude Loudness Measure of how well a sound can be heard Related to Amplitude Larger amplitude = louder sound Smaller amplitude = smaller sound Measured in: Decibels Increasing Amplitude Use an amplifier Table of Decibel scale of sound level