What are the best practices for measuring and reducing cabin noise in commercial flights?

1 Sources of cabin noise

Cabin noise can originate from various sources, both external and internal to the aircraft. External sources include the engines, the propellers, the jet exhaust, the airframe, and the atmospheric turbulence. Internal sources include the ventilation system, the hydraulic system, the electrical system, and the cabin equipment. These sources can generate different types of noise, such as broadband noise, tonal noise, impulsive noise, and structural noise, depending on their frequency, amplitude, and duration.

2 Measurement techniques

To measure cabin noise, engineers use a combination of sensors, microphones, and data acquisition systems. Sensors can measure the pressure, temperature, velocity, and vibration of the air and the structure. Microphones can capture the sound pressure level, the frequency spectrum, and the spatial distribution of the noise. Data acquisition systems can record, process, and analyze the signals from the sensors and microphones. Some of the common measurement techniques are sound intensity mapping, beamforming, modal analysis, and acoustic holography.

3 Noise reduction strategies

To reduce cabin noise, engineers can apply various strategies depending on the source, type and level of the noise. Increasing the distance between the noise source and the cabin, adding insulation and damping materials to the cabin walls and floor, using active noise control systems to generate anti-noise signals, optimizing the design and operation of the noise sources, and implementing noise abatement procedures during takeoff and landing are some of the general strategies that can be employed.

4 Noise standards and regulations

To ensure the comfort and health of the passengers and crew, cabin noise must comply with certain standards and regulations. These are set by various organizations, such as the International Civil Aviation Organization (ICAO), the Federal Aviation Administration (FAA), the European Aviation Safety Agency (EASA), and the International Organization for Standardization (ISO). These standards and regulations specify the maximum allowable noise levels, the measurement methods, and the certification procedures for different types of aircraft and flight conditions.

5 Noise assessment and prediction

To evaluate the effectiveness of the noise reduction strategies and to anticipate the noise impact of new aircraft designs, engineers use various methods of noise assessment and prediction. These methods can be based on empirical models, analytical models, numerical models, or experimental models. Empirical models use statistical correlations and historical data to estimate the noise levels. Analytical models use mathematical equations and physical principles to calculate the noise levels. Numerical models use computational algorithms and software to simulate the noise levels. Experimental models use scaled models and wind tunnels to measure the noise levels.

6 Noise education and awareness

To foster a culture of noise awareness and responsibility among the aviation stakeholders, engineers can engage in various activities of noise education and communication. These activities may include providing information to passengers and crew on how to protect their hearing and reduce their noise exposure, developing training programs for engineers and technicians on aeroacoustics and noise reduction, participating in research projects to share knowledge with other experts, and promoting public awareness of the environmental and social impacts of aircraft noise.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?