Temporary blindness heightens hearing and has potential as a therapy for some deaf people, animal research suggests.
A study, published in the journal Neuron, showed keeping mice in the dark for a week changed their brains and enhanced hearing.
The effect lasted for several weeks after they were returned to the light.
Experts said it was a "fascinating" finding, but making more permanent brain alterations would be key to any new treatments for hearing loss.
The US team at Johns Hopkins University and the University of Maryland compared the hearing of mice that had been kept in complete darkness for a week with that of others getting natural light.
Those kept in the dark could hear softer sounds and there were changes in the structure of the auditory cortex in the brain.
"It was quite a surprise to us," said Dr Patrick Kanold, from Maryland.
One thought was that part of the brain being used for vision was being repurposed, but it seemed the sections dedicated to hearing were being beefed-up.
Dr Kanold told the BBC's Inside Science Programme: "We are not growing any new neurons we are simply strengthening existing connections in the auditory cortex."
"This really give us hope that there might be some potential to apply this in humans, the nice thing is we don't need drugs, so it's relatively straightforward to test.
"This might have implications in deaf people, there's a variety of people that receive cochlear implants as an adult and it might be the case that this enhances the success of these cochlear implants."
It is not certain if the same brain changes would take place in people or if they could reverse the declines associated with old age.
Dr Michael Akeroyd, from the Medical Research Council's Institute of Hearing Research, in Glasgow, told the BBC: "I thought, 'Ooh this is interesting.' I don't know if it's practical, but it's got potential."
He said putting old people with hearing loss into dark rooms for a week or more was unlikely to happen, but that the study added to a growing awareness that there was more to hearing than just the ear.
"Some of most exciting research is that hearing is not just hearing it's listening, there is a burgeoning science in auditory training and developing ways to learn to listen better, it's a real hot topic," he said.
"I would suggest looking for permanent changes next, if you can make it permanent then you're onto a winner."
Dr Ralph Holme, the head of biomedical research at the charity Action on Hearing Loss, said: "This is a fascinating study that tells us more about how our sensory systems interact, in this case how blindness can enhance hearing.
"It is important research because once the mechanisms involved are understood it may be possible to develop training or even pharmacological approaches to boosting these processes to help people with hearing loss.
"More research is now needed to establish if similar findings can be observed in humans and whether or not these changes actually lead to better hearing in the real world."