As has been known for several years, the environment of the International Space Station is relatively noisy. Various operating equipment, environmental control systems and crew activities produce continuous background noise even during astronauts’ rest periods; To this is added the constant exposure to microgravity. What effect do all these factors have on astronauts’ hearing abilities during long space missions? Is it possible to apply measures to counteract the negative effects? Are these side effects, if any, transient or permanent?
The experiment has been trying to answer all these questions since March 2019. Acoustic diagnostics aboard the International Space Station.
Research The developed Acoustic Diagnostics monitors the hearing abilities of ISS crew members before, during and after the flight to detect potential adverse effects of in-flight noise and microgravity on their auditory system.
description
Monitoring the effects of microgravity and the acoustic environment on board the station as a function of time spent on board is important to identify warning symptoms of mild hearing loss. These effects can be temporary or permanent and can lead to even greater hearing loss in future long-term space exploration missions.
Microgravity conditions can affect the body’s hydrostatic balance by increasing fluid pressure in the head and thus disrupting transmission to the middle ear. shell pressure abnormalities Finally, they can damage structures.
Investigative Acoustic Diagnostics It aims to help better understand whether hearing safety is a critical issue for designing future long-term missions and what countermeasures, if any, may be needed. However, performing audiometric tests in a noisy environment such as that of the International Space Station is a sensitive process that requires a certain type of test based on acoustic emissions (AutoAcoustic Emissions. Acoustic emission – OAE).
OAEs are sounds that our inner ear produces in response to an audio stimulus in order to gather information to send to our brain. There are hair cells in the inner ear that act as sensory receptors and respond to external sounds with vibrations; This same vibration produces a very faint sound that echoes in the middle ear and in turn can be captured by special headphones and recorded by the appropriate hardware.
The OAE-based test used in acoustic diagnostic tests is an objective test, does not take into account the active participation of the subject and is not affected by environmental noise, as it uses specific acoustic stimuli. The OAE test is useful to see how well the inner ear and cochlea work.
Luca Parmitano underwent an audio diagnostic test during his post-Held mission between July 2019 and February 2020. Credits: ESA / NASA
The development of portable devices capable of performing accurate audiological diagnoses in noisy environments can also be useful in occupational medicine applications, in noisy industrial environments, to detect temporary or permanent effects on the hearing abilities of workers exposed to noise. Of course, the advanced diagnostic system studied for this study may have various other clinical applications on Earth.
process
Two crew members take three in-flight measurements at two-month intervals; They also take one measurement before the flight and two after the return. After each session, the data is transmitted to Earth. Astronauts must follow a series of events: in-ear calibration, OAE testing, and data transmission through a special program. The duration of each session is 75 minutes. The subject turns on the laptop and puts on headphones to take sound measurements and uses the Astronaut Everywhere app to answer the questionnaires.
Outline diagram of the acquisition system for intraorbital enhanced acoustic diagnostics (Acoustic diagnostics). Credits: Arturo Moleti
European astronaut Matthias Maurer undergoes an acoustic diagnostic test on January 24, 2022.
Developed by the Department of Physics Tor Vergata of the University of Rome, sponsored by the European Space Agency, the experiment runs from March 2019 to September 2023 and includes missions 59/60, 61/62, 63, 65, 66, 67, 68 and 69. Like her colleagues who preceded and will follow her, Samantha Cristoforetti will also participate in this and other experiments planned during her mission in Minerva.
In the next two videos, it is possible to constantly notice the background noise that characterizes the middle of the USOS (tropical United States) part of the station. It’s a bit outdated, but the current audio situation hasn’t changed much today.
In this other video we can see the biggest noise from the Russian side of the station.
Sources: NASA; Wikipedia
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