ISS commander Pavel Vinogradov works in the Zvezda service module, where noise levels are between 62 to 69dB (Image: NASA)

Six years after launch, the International Space Station’s living quarters are still noisier than they should be. Now Russian news reports say that astronaut Bill McArthur and cosmonaut Valery Tokarev returned from their six-month stay aboard the ISS in April 2006 with some hearing loss.

NASA will not discuss the health of individual astronauts, but spokesperson Kylie Clem told New Scientist: “It’s not an impedance to operations or crew health or safety. It’s more of a comfort level issue.”

Former astronaut Jay Buckey, now at Dartmouth Medical School in Hanover, New Hampshire, US, says that both temporary and permanent hearing loss were recorded after flights on the Soviet and Russian Salyut and Mir stations, even for stays as short as seven days. The lost hearing was usually at higher frequencies.


The living quarters of the ISS are the Russian Zvezda module, which is the noisiest module on the station. NASA says the goal is for the working area to have noise levels at or below 60 decibels (dB) and sleep bunks to be 50dB. At their peak several years ago, noise levels reached 72 to 78dB in the working area and 65 dB in the sleep stations. Decibels are measured on a logarithmic scale, meaning, for example, that 60dB is 10 times louder than 50dB.

NASA has worked to reduce the noise and its effect on the crew. By November 2005, noise levels had been lowered to between 62 to 69dB in the work area and 55 to 60dB in the sleep compartments. Astronauts on the ISS used to have to wear ear plugs all day but are now only wear them for 2 to 3 hours per work day.

Intracranial pressure

According to the US National Institutes of Health, however, noise levels below 80dB are unlikely to lead to hearing loss, even with prolonged exposure.

But while the primary cause of hearing loss in general is high noise levels, Buckey suggested in a 2001 paper in Aviation Space and Environmental Medicine that several other factors might contribute to the problem in space.

Elevated intracranial pressure, higher carbon dioxide levels and atmospheric contaminants may make the inner ear more sensitive to noise, he says. But there have been no studies yet to test these ideas.

Buckey had designed a device to measure hearing loss of astronauts on the ISS, but his project was cancelled around the start of 2006 when NASA reduced funding for life sciences.

NASA has already done much of what it can to reduce noise on the ISS. Crews have installed fan vibration isolators and mufflers on fan outlets, and acoustic padding to wall panels.

The current crew, Russian cosmonaut Pavel Vinogradov and US astronaut Jeff Williams, installed a sound-insulating cover on the Russian carbon dioxide removal system. They also started adding acoustic padding near the Russian air conditioner. Future crews will swap out 30 to 40 fans with quieter versions.