Regularly using a mobile phone may increase the risk of tinnitus, which involves constant ringing or buzzing in the ear, a small study suggests.
Austrian researchers recruited 100 people with the condition and 100 without, and compared mobile phone use.
They found tinnitus was over 70% more likely in those averaging 10 minutes' daily phone use, reported Occupational and Environmental Medicine journal.
But the British Tinnitus Association said a link was unproven.
While intense noise, head trauma and certain drugs are all known to increase the risk of the ear condition, in many cases the reasons are unknown.
Researchers from the Medical University of Vienna said the evidence so far linking mobiles with tinnitus was anecdotal, but that their small study suggested at the very least it warranted further investigation.
Because of the widespread use of the devices, even a slightly increased risk would be of "public health importance", they wrote, particularly given that the condition can in some cases profoundly interfere with daily life.
It is thought about 10% of the population have some form of tinnitus, but it is unclear whether the condition is becoming more prevalent.
As well as the 70% increased risk from using a phone for more than 10 minutes a day, they found that having used a phone for more than 160 hours cumulatively was associated with a 60% increased risk.
But their study did throw up statistical anomalies, finding a lower risk among those who had made 4,000 calls or more than those who had made fewer.
The team acknowledged that asking people to recall their use was problematic, leading to both over-estimation and underestimation.
But lead author Dr Hans Peter Hutter said there were biological mechanisms by which mobiles could cause ear problems.
The cochlea, the spiral-shaped organ that translates sounds into electrical impulses the brain can understand, and the auditory pathway "are located in an anatomical region where a considerable amount of the power emitted by mobile phones are absorbed".
It is also possible that prolonged, constrained posture using a phone while walking and talking could affect blood flow in that side of the head.
These reasons are more likely than simply the sound of speech on the other end of the line.
Veronica Kennedy, a consultant and adviser to the British Tinnitus Association, said: "The association between tinnitus and electromagnetic fields is not a new idea with electromagnetic fields being put forward both as a cause and treatment for tinnitus.
"Some people have attributed their tinnitus to the sounds generated by electromagnetic fields within modern electrical wiring or power plants. Electromagnetic therapy has also been used to treat tinnitus. This is an interesting study but there are a number of complex factors underlying tinnitus which have not been addressed in the study.
"The link between mobile phone use remains unproven with further work still needed."