Presently, millions of people of all ages in the United States are suffering from deafness. Even a minor degree of hearing loss in school-going children results in impaired learning at school. This study was conducted to analyze the changing trends in the prevalence of hearing loss in adolescents over a certain period. In addition, the researchers of this study also evaluated the type of deafness in the participants and the possible causes for deafness. “The prevalence of hearing loss among a sample of U.S. adolescents aged 12 to 19 years was greater in 2005-2006 compared with 1988 to 1994.”
The National Health and Nutrition Examination Survey (NHANES) is conducted regularly in the United States to examine the overall health status of the country. As a part of the collection of health-related data, even the hearing capacity of individuals is assessed. The present study obtained data from the NHANES conducted from 1988 to 1994 and the NHANES conducted in 2005-2006. The researchers specifically looked for data related to the hearing ability of adolescents aged between 12 and 19 years. They also evaluated at which frequencies of sound the adolescents felt more change in their hearing capacity. The researchers also examined the intensity of the hearing loss. They looked for the causes, such as infection and loud sounds, which led to the deafness.
* The NHANES surveys conducted from 1988 to 1994 included 2,928 participants and the NHANES survey conducted from 2005-2006 included 1,771 participants who were aged between 12 and 19 years. The individuals who had cochlear implants or those who were using hearing aids were excluded from the study.
* Hearing ability was assessed in both the ears by using an audiometer. This measurement was done at frequencies 0.5, 1, 2, 3, 4, 6, and 8 Hz. Different intensities of sounds varying from -10 dB to -120 dB were used.
* Demographic parameters, such as race, income and sex of the participants were noted. Data regarding exposure to loud music and occurrence of ear infection were also collected.
* There was no difference with regard to age, sex and race between the two studies.
* Hearing loss among 12- to 19-year olds was 14.9 percent from 1988 to 1994 and 19.5 percent in 2005-2006. Hence, a 31 percent rise in the incidence of deafness was observed. Unilateral and bilateral deafness were 11 and 3.8 percent from 1988 to 1994 and 14 and 5.5 percent in 2005-2006, respectively. The loss of hearing with regard to high-frequency sound was found to be higher in the 2005-2006 survey.
* Mild and severe hearing losses were 11 and 3.5 percent, respectively from 1988 to 1994 and 14 and 5.3 percent respectively, in 2005-2006.
* The incidence of ear infections was slightly more from 1988 to 1994. The prevalence of deafness was slightly high in females in 2005-2006. No association between exposure to loud sound and hearing loss was observed.
The definitions of hearing loss keep changing from time to time. Different investigators use different cutoff values to define deafness. Hence, the evaluation and comparison of deafness is a complicated task. Moreover, ear examination was not performed in the 1988 to 1994 surveys. Sometimes, even the presence of wax produces mild impairment in hearing. Children with hearing aids and cochlear implants were not included in the study. This leads to a false decrease in the prevalence of deafness.
This study has shown that the incidence of deafness is on the rise in adolescents aged 12 to 19 years. However, this study has failed to clearly identify the cause for such a rise in the prevalence of hearing loss. The finding that there is an increase in hearing loss for higher frequencies indicates that the rise in deafness is because of exposure to loud noise. Follow-up studies, which evaluate the hearing capacity in those who are exposed to loud sound, may show an association between hearing loss and loud noise. An earlier study conducted in Australia has shown that use of stereo devices led to 70 percent increase in the risk of developing hearing loss. Further studies have to be performed to confirm these findings and to find out other risk factors. The identification of causes for increasing hearing loss may be helpful in preventing further rise in the prevalence of deafness.
For More Information:
Change in Prevalence of Hearing Loss in U.S. Adolescents
Publication Journal: Journal of American Medical Association, August 2010
By Josef Shargorodsky; Sharon G. Curhan; Brigham and Women’s Hospital, Boston, Massachusetts
*FYI Living Lab Reports Are Summaries of the Original Research.