Low-frequency noise from MV-22 Osprey at take-off exceeds assessment standard

October 05, 2012 Ryukyu Shimpo

In the morning of October 4 when MV-22 Osprey training began at Futenma Air Station, a team led by Takeshi Tokashiki, an associate professor the University of the Ryukyus conducted a noise survey on the occurrence of low-frequency sound recorded at take-offs. The level of sound recorded was higher than that stated in the environmental impact assessment created by the Ministry of Defense for the Futenma relocation plan to Henoko. The team confirmed the level of low-frequency sound at the first landing of the aircraft on the base, with Tokashiki stating that the aircraft “clearly generated low-frequency sound.”

Tokashiki carried out the survey on the roof of No. 2 Futenma Elementary School, which is located near Futenma Air Station. At 11:40am on October 4, 85.8db at 16 hertz was recorded, which is 8.8db higher than the threshold value for physical impact stated in the assessment. Some physical impact causes rattling of buildings and vibration, and amplifies the psychological impact on people. In terms of the level of psychological impact, which can result in headaches, irritability and nausea, the aircraft recorded 83.7db at 40Hz, 5.7db higher than the threshold value of the assessment.

A CH-46 helicopter that took off at 10:27am that same day also generated low-frequency sound, some of which reached 81.5db at 40Hz, which exceeded the stated threshold of 78db at 40Hz. However, the figure caused by the CH-46 was less than that of the Osprey.

(English translation by T&CT, Mark Ealey)

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