Effects of noise on crewmembers during Spacelab Life Sciences-1.

Abstract

Excessive noise can lead to decrements in performance, impaired verbal communication, fatigue, and hearing damage. On the STS-40/SLS-1 mission noise levels were evaluated through the use of a questionnaire and two objective measures−in-flight sound level measurements and pre- and post-flight crew audiometry tests. Sound level meter measurements suggested that noise levels in Spacelab during nominal operations were approximately 70 dB (A-weighted). This is in excess of the current acoustic specification of 59 dB (A-weighted). Noise measurements conducted in the Orbiter did not exceed current Shuttle standards. Crewmembers recommended that noise levels be reduced. Post-flight audiometry tests indicated that transient decreases in hearing ability had taken place during the mission. The average decrease in hearing level of 4.34 dB was statistically significant. Crewmembers noted that sleep, concentration, and relaxation were negatively impacted by high noise levels. Communication was also hampered. The higher than desirable noise levels in Spacelab were attributed to flight specific payloads for which acoustic waivers were granted. It is recommended that current noise levels be reduced in Spacelab and the Orbiter Middeck. Levels of NC 50 are recommended in areas where speech communication is required, and NC 40 in sleep areas−in accordance with current Space Station Freedom standards. [This research was supported by the National Aeronautics and Space Administration under Contract No. NAS9-17900.]

Short‐duration space flight and hearing loss

“…It should also be borne in mind that all of this noise occurs within the confined space available whether on Shuttle or Station. The laboratory section of STS-50, for example, measured 7 m in length with an outside diameter of 4 m, with the habitable volume significantly reduced by experimental equipment 4 …”

“…Excessive noise during Shuttle missions and on the ISS creates problems for the crew in 3 major areas: interference with sleep, annoyance, and speech interference 2–4 . For symptomatic relief of the first 2 problems, hearing protection in the form of foam ear plugs is provided to astronauts.…”

“…Considering the degree of noise to which astronauts are exposed, it is not unreasonable to expect a degree of noise-induced hearing loss. NASA technical reports have attempted to address this problem for both the Shuttle and ISS, 2–4 primarily with measurements made of noise levels and estimates of potential effects on hearing. It has been reported that “ there is no data to positively conclude that continuous noise exposure, in the ranges experienced… will cause Permanent Threshold Shift.” 3 No reports of hearing data for US astronauts have been published in the medical literature.…”