Understanding Sound Waves

Visual Representation of Sound Waves

• Sound waves in air: Represented by air molecules moving back and forth.
• Oscilloscope representation: Displays sound wave as a graph.
  • Horizontal axis: Time
  • Vertical axis: Displacement of air molecule
  • Center line: Equilibrium/undisturbed position of air molecule

Key Concepts in Sound Waves

Amplitude

• Definition: Maximum displacement from the equilibrium position.
• Important: Amplitude is not the total length of displacement, just the maximum.
• Relation to Volume: Larger amplitude results in louder sound.

Period

• Definition: Time for one complete oscillation (back and forth cycle).
• Measurement: In seconds, denoted by capital T.
• Influence on Pitch: Decreasing the period (faster oscillations) increases the pitch.

Frequency

• Definition: 1 over the period, number of oscillations per second.
• Unit: Hertz (Hz), where 1 Hz = 1 oscillation per second.
• Example: A note at 440 Hz means 440 oscillations per second.
• Human hearing range: Approximately 20 Hz to 20,000 Hz.
• Dogs can hear up to 40,000 Hz.

Wavelength

• Definition: Distance between two compressed regions in a sound wave.
• Measurement: In meters.
• Distinction from Period:
  • Wavelength is spatial (distance), while period is temporal (time).
  • Period involves time for one cycle, wavelength involves distance between compressions.

Graphical Representations of Sound Waves

Displacement vs. Time Graph

• Shows air molecule activity over time.
• Peaks represent the period of the wave.

Displacement vs. Position Graph

• Snapshot of air molecule displacement at a specific point in time.
• Peaks represent the wavelength, not the period.
• Demonstrates spatial displacement along the wave.

Summary

• Understanding the graph and terms such as amplitude, period, frequency, and wavelength is crucial in analyzing sound waves.
• Differentiating between graphs and what they represent (period vs. wavelength) is key to understanding sound wave behavior.