NA-39A environmental noise monitorThis automated aircraft noise monitoring system is capable of calculating evaluation values according to the Environmental Standard Related to Aircraft Noise. The real-time 1/3 octave band analysis function provided as a standard feature allows more detailed analysis and enables the acquisition of GPS location information and automatic time calibration. The collected data can be processed with the aircraft noise management software for data compilation, viewing, and creating reports. It is one third of the size of the conventional model (NA-37), and has half of its power consumption. The system has been updated to allow long-term, continuous monitoring of measurement information with greater precision.AN-39D noise arrival direction identification unitThis device determines the arrival direction of aircraft noise and ground-based noise by measuring the elevation angle and azimuth angle using its four microphones. By measuring the position and movement of the sound source, it can then determine with high precision whether the sound is ground-based or aircraft noise.Visualization of how ground noise is generatedVarious types of ground noise are generated at airports. Among the loudest come from the thrust reversers used when airplanes are landing and the semi-constant superimposed engine noise from numerous aircraft taxiing to and from the runway, which creates a high noise background. These ground noises need to be identified and distinguished from aircraft noise.with the region, was one of the people who supported the project from the sales perspective. She recalls the situation in Vietnam around 2018.“Those were the days when aircraft noise started to be regarded as a social issue by the Vietnamese government and environmental experts but hadn’t yet been widely recognized by the general public. The results of a survey done around Tan Son Nhat Airport in the sub-urbs of Ho Chi Minh City indicated the residents around the airport were very concerned about the noise, with some describing it as unbearable. During my own visits, I experienced the roar of com-mercial planes passing overhead every three minutes or so. The issue was obvi-ous. Although one may become accus-tomed to noise, continuous exposure can lead to hearing loss, thus I felt this was an urgent environmental issue that needed to be addressed.”Generally, and not limited to Vietnam, areas around airports tend to attract peo-ple from rural areas looking for commer-cial opportunities. Most areas are inhab-ited by the economically vulnerable, and their voices on environmental issues tend to be ignored. So, it was of major social significance to promote this aircraft noise monitoring project.4Protecting residents from unbearable noise“The Vietnam Project seeks to share aircraft noise measurement technologies with engineers in Vietnam and to jointly prepare an aircraft noise measurement manual,” says Keishi Sakoda of the Field Engineering Department. “The project got started as a JICA Collaboration Pro-gram with the Private Sector for Dissem-inating Japanese Technologies for devel-oping countries, with Mr. Oya of Rion’s Technical Development Center serving as project leader. I was in charge of lead-ing the technical aspects of the project.” In September 2018, an agreement was signed between Rion, the Civil Aviation Authority of Vietnam, and the Airports Corporation of Vietnam on technical joint efforts to establish technologies for monitoring and measuring aircraft noise. Various experts, including Mr. Yamada (our advisor at the time), who contribut-ed significantly to the development of technologies for measuring and evaluat-ing aircraft noise and has been active in making proposals on environmental issues associated with aviation, provided project support.Aya Ishida of the International Sales Department, who visits Vietnam every two to three months and is quite familiar Laying the foundations for aircraft noise monitoring in Hanoi, VietnamThe first aircraft noise monitoring system in Vietnam was installed at Noi Bai International Airport in November 2018, two months after the signing of the agreement. The airport is the largest one in the north, located in the capital city of Hanoi. Then the preparation of a mea-surement evaluation manual and the education and training of the measuring technicians began. Normally, the compo-sition of a system to be delivered is deter-mined based on the structure of the air-port and the results of the measurement data. But since this installation was mainly for training purposes, we shipped a set of four aircraft noise monitoring sta-tions and a computer for data processing. The core equipment was the AN-39D, which uses four microphones to detect aircraft noise, among other sounds, and the NA-39A, which performs measure-ments and records data. The system also included the MS-11A, an outdoor micro-phone unit suited for long-term, continu-ous measurement (including a heater for suppressing condensation, the main cause of sensitivity variation, to maintain performance, and a built-in test sound source for automatic calibration). These latest instruments from Rion helped the
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