Likely infra-sound at Various Distances

• Sound below 20 Hz (infrasound) receives little attenuation traveling through air, barriers or any other means that may be used to reduce audible noise
• 78 dB at 0.5 mile (from previous chart gas turbine)
• Decreases approximately 6 dB for every 2x distance
• At 1 mile from source – 72 dB
• At 2 miles from source – 66 dB
• At 4 miles from source – 60 dB
• 85 dB at 0.25 mile (Siemens SGT-800 45 MW gas turbine with “best available” damping)
• Decreases approximately 6 dB for every 2x distance
• At 0.5 mile from source – 79 dB
• At 1 miles from source – 73 dB
• At 2 miles from source – 66 dB
• At 4 miles from source – 60 dB
• Undamped sound from SGT-800 gas turbine 45 MW electric generator is 130-150 dB, Siemens data indicates damping to 85 dB is possible.