Sept. 19, 2007 -- Long-time mobile phone users who talk more than an hour a day on the devices may be may be more likely to have high-frequency hearing loss, researchers say.
"Our intention is not to scare the public," says Naresh K. Panda, MS, DNB, chairman of the department of ear, nose, and throat at the Post Graduate Institute of Medical Education and Research in Chandigarh, India, and researcher for the study. The study, he tells WebMD, is preliminary and small. "We need to study a larger number of patients."
He presented the findings Wednesday at the annual meeting of the American Academy of Otolaryngology -- Head and Neck Surgery in Washington.
His team found that people who had talked on cell phones for more than four years and those who talked more than an hour daily were more likely to have these high-frequency losses. These losses can make it difficult to hear consonants such as s, f, t and z, making it hard to understand words.
But another hearing expert familiar with the study says there is as yet no cause for alarm.
Hearing Loss Study
Panda and his colleagues evaluated 100 people, aged 18 to 45, who had used mobile phones for at least a year, dividing them into three groups according to length of use. One group of 35 had used phones for one to two years; another group of 35 had used them for two to four years, and a group of 30 had used them for more than four years.
"We asked them if they had been using the phones less than 60 minutes or more than 60 minutes per day," Panda tells WebMD. They compared the phone users with 50 people who had never used cell phones and served as a control group. The study was conducted in India.
Those who used the mobile phones for more than four years had more hearing loss in high-frequency ranges in their right ear, the ear most held the phone to, than those who used the mobile phone for one to two years.
"When we compared high-frequency thresholds (the level at which the sound is first detected) between the one- to two-year [users] and more than four years; there was a significant difference in the thresholds between these two groups," he says.
One- to two-year users had a 16.48 decibel loss in the high-frequency range, he says, while those who used the phones more than four years had a 24.54 decibel loss.
That decrease in hearing over a relatively brief period may not be noticeable to mobile phone users but would be of concern to a hearing expert, says Andy Vermiglio, AuD, a research audiologist at House Ear Institute in Los Angeles.
Mobile phone users who had symptoms such as a warm sensation, fullness in the ears, or ringing were more likely to have the high-frequency hearing loss, Panda also says.
Long-term mobile phone use may result in inner ear damage, Panda speculates. And symptoms such as ear warmth or fullness could be early warning signs of that damage.