Ospreys eight times louder than the CH-53 helicopter

Ospreys eight times louder than the CH-53 helicopter

The low-frequency noises from the MV-22 Osprey and CH-53 helicopter surveyed at the Second Futenma Elementary School.Brown bar graph for the Osprey and blue for the CH-53 helicopter.Parallel line: frequency (hertz) and vertical line: noise level (decibel).

May 27, 2014 Ryukyu Shimpo

Takeshi Tokashiki, an associate professor at the University of the Ryukyus, has surveyed the frequency of noise emitted by the MV-22 Osprey and CH-53 helicopters stationed at the U.S. Marine Corps Futenma Air Station. The survey revealed the Osprey aircraft’s noise was louder than the CH-53 by about 30 decibels.

This is the first time researchers have carried out a survey on the noise frequency of both aircraft under the same weather and time conditions.

According to Tokashiki, the 30 decibel difference between the Osprey and the CH-53 translates to about eight times the noise level to the human ear.
Tokashiki carried out the survey on the roof of the Second Futenma Elementary School in Ginowan on May 16.

He surveyed low-frequency noises emitted by the Osprey at 9:16 a.m. and the CH-53 helicopter at 9:28 a.m. when both the aircraft took off. At 63 hertz, the noise of the Osprey was 99.4 decibels, and that of the CH-53 helicopter was 70.2.

Low-frequency noise is sound that is lower in frequency than 100 hertz. It can cause headaches or sickness and shake fittings.

The survey detected noise higher than the threshold level stipulated in the environmental assessment report created by the Okinawa Defense Bureau for the Henoko relocation. Tokashiki asserted, “We confirmed the low-frequency noise from the Osprey by comparing with the CH-53 helicopter.” Referring to the fact the assessment report did not survey the low-frequency noise from the Osprey, he stressed the importance of carrying out a precise survey on the noise.

(English translation by T&CT)

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