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Decibel Change vs Distance Equation:
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The decibel vs distance equation calculates the change in sound level (in decibels) when the distance from a sound source changes. It's based on the inverse square law which states that sound intensity decreases by 6 dB for each doubling of distance from the source.
The calculator uses the decibel change equation:
Where:
Explanation: The equation calculates how much the sound level changes when moving from distance r₁ to distance r₂ from a sound source.
Details: This calculation is essential for audio engineering, noise control, environmental noise assessment, and understanding how sound propagates in different environments.
Tips: Enter both distances in meters. The calculator will determine the decibel change between the two distances. Both values must be positive numbers.
Q1: Why is the coefficient -20 used in the equation?
A: The -20 coefficient comes from the relationship between sound pressure level (which uses 20log₁₀) and the inverse square law for sound intensity.
Q2: What does a negative result mean?
A: A negative result indicates sound level decrease (quieter), while a positive result indicates sound level increase (louder) when moving between distances.
Q3: Does this equation work for all sound sources?
A: This equation works best for point sources in free field conditions. Real-world environments with reflections and absorption may show different results.
Q4: How accurate is this calculation?
A: The calculation is mathematically precise for the inverse square law model, but actual sound propagation may vary due to environmental factors.
Q5: Can I use different units for distance?
A: Yes, as long as both distances use the same units (meters, feet, etc.), the ratio r₂/r₁ will be the same and the calculation will be valid.