This study was conducted by US researches in Boston, Massachusetts, and Nashville, Tennessee. It was funded by the Massachusetts Eye and Ear Infirmary Foundation and Vanderbilt University School of Medicine. The study was published in the Journal of the American Medical Association (JAMA).
Studies on more than 1200 students have shown that even slight hearing loss in the young is linked to lower scores on communication tests, decreased self-esteem, and increased stress. Surveys in Europe and UK shows that nearly 90% young people use iPods and other personal music players and many listen at maximum volume for several hours a day. Earphones that insert into the ear canal further amplify the sound, which can exceed 120 decibels - comparable to the noise of a jet engine.
For this study researchers compiled data from two phases of a large, recurring study looking at the health of Americans (National Health and Nutrition Examination Survey, or NHANES). Data on hearing tests given to adolescents aged 12 to 19 during two phases of the survey: from 1988-1994, and from 2005-2006 was analysed. Results showed that in the 1988-1994 survey, 14.9% of adolescents had some hearing loss. This rose to 19.5% in the 2005-2006 survey - a 31% increase over time, say the researchers. The percentage of those with mild or worse hearing loss rose by 77%, indicating that 1 in 20 young people may now have worse-than-slight hearing problems.
Some factors they thought responsible included repeated ear infections and listening to loud music for five or more hours a week. However, no significant association with these factors was noted in the study. The researchers did find a link between being very low-income (below the poverty line) and an increased risk of hearing problems. However, hearing loss in 2005-2006 survey was mainly loss of high-frequency hearing that has been linked to loud-noise exposure.
Study author and lead researcher Josef Shargorodsky, a physician-investigator at the Channing Laboratory at BWH said, "We have known for a few years that hearing loss is very common in US adults... However, an understanding of hearing loss in adolescents can help to paint a better picture of overall hearing loss in the US, and aid in further identifying potential causes of hearing loss." He added, "What makes hearing loss in adolescents even more concerning is previous research showing that teens underestimate the importance of hearing and the dangers of noise exposure, and don't make protecting their hearing a priority." This fact he explained was found in previous studies that hearing loss ranked low as a health concern.
