As has been known for several years, the surroundings of the International Space Station are 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 the astronauts’ hearing abilities during long-term space missions? Is it possible to implement countermeasures to counteract any negative effects? Are these adverse effects, if any, transient or permanent?
To all these questions, the experiment tries to answer from March 2019 Acoustic diagnosis on board the International Space Station.
Research Developed orbital acoustic diagnosis (Acoustic Diagnosis) monitors the hearing abilities of ISS crew members before, during, and after flight to detect possible adverse effects of in-flight noise and microgravity on their auditory system.
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 the warning symptoms of a mild hearing impairment. These effects can be temporary or permanent and can cause even greater hearing damage in future long-range 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 anomalies. Finally, they can damage structures.
Research Acoustic Diagnosis Aims to help better understand whether hearing safety is a critical issue in designing future long-term missions and what countermeasures, if any, may be needed. However, performing audiometric tests in a noisy environment such as 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 with the goal of gathering information to send to our brain. In the inner ear there are hair cells that act as sensory receptors and respond to external sounds with vibration; This same vibration produces a very faint sound that reverberates in the middle ear and, in turn, can be picked up by special headphones and recorded by the right hardware.
The OAE-based test used in acoustic diagnostic research is an objective test, does not take into account the active participation of the subject and is not affected by environmental noise because it uses specific acoustic stimuli. An OAE test is useful to see how the inner ear and cochlea work.
Luca Parmitano undergoes an audio diagnostic test during his mission behind Held between July 2019 and February 2020. Credits: ESA / NASA
The development of portable devices capable of making accurate audiological diagnoses in a noisy environment could 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 research could also have other clinical applications on Earth.
Two crew members make three measurements during the flight with an interval of two months; They also do one measurement before the flight and two after the return. After each session, the data is transmitted to Earth. Astronauts must follow a specific set of events: calibration in the ear canal, 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 use the Astronaut Everywhere app to answer the questionnaires.
Schematic of the acquisition system for an Enhanced Acoustic Diagnostics intraorbital assay. Credits: Arturo Moletti
European astronaut Matthias Maurer undergoes an acoustic diagnostic test on January 24, 2022
Developed by the Department of Physics at the University of Rome Tor Vergata, 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 take part in this and other experiments planned during her mission to Minerva.
In the following two videos, it is possible to constantly notice the background noise that characterizes the environments of the USOS part (tropical part of the United States) from the station. It’s a bit out of date, but the current audio situation hasn’t changed much today.
In this other video we can see the loudest noise on the Russian side of the station.
Sources: NASA; Wikipedia, the free encyclopedia
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