Visualizing and quantifying aircraft cabin noise
Within the aircraft cabin, acoustic engineers encounter distinctive obstacles in their quest to create a pleasant and comfortable auditory environment for passengers. The constant hum of engines, disruptive airflow noises, and vibrations pose significant challenges in achieving optimal acoustics. This case study delves into troubleshooting techniques and highlights how Lufthansa successfully identified crucial points of interest, enabling them to overcome these hurdles and deliver a comfortable experience for air travelers.
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Lufthansa
Lufthansa, a renowned global airline, leads the aviation industry with its commitment to excellence and innovation. With a vast history and worldwide reach, Lufthansa serves millions of passengers annually, offering premium air travel services. To ensure a quiet and comfortable travel experience, Lufthansa collaborates with Microflown, leveraging their advanced technology and expertise. Together, they localize noise sources, with the aim to achieve quieter cabins, elevated passenger comfort, and a superior standard of air travel for valued customers.
GOAL & REQUIREMENTS
Lufthansa seeks to enhance the acoustic environment within the airplane cabin through this feasibility study aimed to drive innovation and improve the overall acoustic environment for a more comfortable travel experience.
• Detecting sound sources and leakage in an airplane cabin interior
MEASUREMENT METHODOLOGY
This case study utilized two measuring solutions to tackle acoustic challenges. The Voyager, a portable multi-channel acoustic analyzer, captured data through listening tests conducted by scanning with a PU probe near the cabin panels. The evaluation encompassed sound pressure and particle velocity signals. Real-time filtering tools were employed to concentrate the output on specific frequency bands of interest. Leveraging the distinctive capabilities of particle velocity proved invaluable in the field, particularly for detecting acoustic leakages
Once this was done the team switched to Scan&paint3D to efficiently scan an entire cabin section in just around 30 minutes. To achieve this, multiple measurements were taken of each sub-section individually, with an average measurement duration of approximately 4 minutes. This approach ensured accurate and detailed analysis of the sound field in the cabin, providing valuable insights for effective noise control and troubleshooting efforts.
500 hz
The results of this region are very similar to the previous band, the radiation area is located at the intersection of the floor with the cabin wall panel. But with the difference that at the top and very centralized there is a prominent radiation spot coming from the partition between the wall and the luggage carrier.
4khz
The upper and lower sections show similar behavior to previous bands. The left window, close to the outside speaker, is a significant radiation area for this frequency band too. Radiation/leakage is concentrated around the bottom sides of the window. Particularly, there is a specific area at the far right where the panel bottom walls intersect, showing strong radiation.
OUTCOME OF THE MEASUREMENT CAMPAIGN
Despite the challenging acoustic conditions in the target environment, sound source localization and quantification was performed effectively in the full audible range without introducing any extra absorption material into the cabin. The results were used to inform potential construction changes.
Key findings of this investigation are:
• The Voyager has effectively identified key noise sources and regions of interest.
• The integration of the Voyager with the Scan & Paint 3D solution has facilitated comprehensive identification of noise and leakage sources, providing a visual representation of the entire sound field.
• The most significant radiation/leakage per frequency band is observed at the intersection between the floor and cabin wall. Other source/leakage areas largely coincide with intersections involving other panels, the floor, and windows.
• Faster scanning has demonstrated effectiveness in achieving reliable results
Scan&Paint 3D
Voyager