How can you model aircraft noise propagation to the ground?

Modelling aircraft noise propagation to the ground involves complex calculations & considerations. Developed by FAA, a commonly used method is the Integrated Noise Model (INN). Process includes: ? Source noise generation— determine the noise characteristics of the aircraft, considering engine types, thrust settings, configurations. Use data such as the aircraft's noise footprint & spectral content. ? Flight path and altitude data—understand the impact of takeoff, speed, landing & in-flight phases on noise generation ? Atmospheric conditions—temperature, humidity & wind speed, as they influence sound propagation ? Ground reflection & absorption—account for the reflection/absorption of sound waves by the ground, different absorption coeff

One thing I've found helpful is utilizing comprehensive aircraft noise propagation models, like Integrated Noise Models (INM) or Community Noise Equivalent Level (CNEL), which consider diverse noise sources such as engine, airframe, and aerodynamic noise. These models, when factoring in environmental conditions and topography, offer accurate predictions of how aircraft noise propagates to the ground, aiding in strategic planning for noise mitigation.

It's important to note that accurate modelling requires detailed data, including aircraft specifications, flight profiles and environmental conditions. Additionally, local regulations & community concerns may influence the parameters and metrics used in the modelling process. Advanced software tools & expertise in acoustics are typically employed to conduct these analyses.

High fidelity simulations can help but the cost is very high. It's possible to optimize sound quality with mixed approach in which the actual part is combined with simulation. The NVH is a very mature field and best practices consolidated in the automotive industry can be adapted to the aeronautical one.

Calculate noise metrics such as maximum noise level, equivalent continuous noise level, and other standardised metrics based on regulatory requirements. Additionally use mathematical models to simulate the propagation of noise from the aircraft to the ground. Incorporate ground effects, atmospheric conditions, and topographical features in the model. Consider distance decay as it accounts (inverse square law) for the spreading of sound waves. Consider population density in the surrounding areas to estimate the potential impact on communities. Validate the model against actual noise measurements in the vicinity of airports to ensure accuracy and reliability.

Noise quality can be addressed considering it as a KPI at design stage. High fidelity multi physical simulation allows to get an holistic approach. Advanced optimization tool are available to pursue an integrated design where we can control, at the same time, many KPI (noise, life, range, sound quality, weight, cost, ...).

By default, Supersonic flying or cruise is prohibited over human habitat - land et al due to the boom effect. Meaning : Air-pressure waves at high speeds similar to the water waves caused by a ship's bow cause the loud noise - Boom. If the waves are distorted while flying, then boom doesn't occur or produces non boom noise. By ionising the air surrounding aircraft and using magnetism to deflect it in such a way boom does not occur, then the air pressure waves become distorted resulting in a non boom noise.

Explore mitigation measures, such as altering flight paths, adjusting operational procedures, or implementing noise abatement technologies