When used continuously for more than an hour, portable MP3 players can cause short-term hearing loss in listeners.
"It is well known that excessive occupational noise exposure can lead to noise-induced hearing loss. Excessive noise exposure can lead to metabolic and/or mechanical effects resulting in alterations of the structural elements of the organ of Corti [the inner ear organ in mammals that contains auditory sensory cells or 'hair cells']," The Telegraph quoted Hannah Kempler, of Ghent University, Belgium as saying.
"The primary damage is concentrated on the outer hair cells, which are more vulnerable to acoustic over stimulation that inner hair cells," Kempler added.
Participants in the study had their hearing tested and were then asked to listen to pop or rock music for six one hour long sessions using two different types of headphones and at varying, preset volumes.
A control group of 14 people of the same ages was used to compare the results.
The study is published in the June issue of Archives of Otolaryngology-Head and Neck Surgery.