Original ResearchHearing risk associated with the usage of personal listening devices among urban high school students in Malaysia
Introduction
The usage of personal listening devices (PLDs) such as mp3 players and mobile phones with a music playback function has become increasingly popular worldwide, with estimated sales of 245 million units in 2012.1 New-generation PLDs have a long battery life, permit storage of a large number of songs, and are capable of producing high sound output levels without distortion. These features allow current PLD users to listen for longer durations and at higher volumes. The high-risk users are teenagers and young adults; prolonged exposure to loud music in these listeners could potentially damage their hearing.2
The maximum sound output level from PLDs can reach 100–120 decibels in A-weighted scale (dBA)3, 4, 5, 6 which is equivalent to sound levels produced by a jackhammer or a chain saw. At high volumes, sound exposure from PLD use could easily exceed the safety limit set for occupational noise exposure levels for acquiring noise-induced hearing loss (NIHL), even if only used for a short duration.4, 6 Compared with non-users, PLD users have reportedly shown evidence of subtle cochlear outer hair cell damage3, 7, 8 and poorer high frequency hearing thresholds.9, 10, 11 It is estimated that up to 5–10% of PLD users may eventually develop some form of permanent hearing impairment after years of PLD use.2 Considering the fact that hundreds of millions of PLDs are sold worldwide, even if a small percentage of users were to listen at unsafe levels, this would potentially put millions at risk of NIHL and pose a significant public health issue.12, 13
The popularity of PLD usage globally has also found its way to Malaysia. Due to their affordability and appeal, PLDs have become a must-have gadget for Malaysian teenagers. This study investigated listening habits associated with the use of PLDs in a group of urban high school students in Klang Valley, Malaysia and evaluated the impact on their hearing.30
Section snippets
Subjects
Subjects aged 13–16 years were recruited from three schools selected at random from a list of high schools located within 20 km of the authors' university. The appropriate sample size was calculated based on Krejcie and Morgan's sample size determination table.14 Study participants responded to flyers distributed in classrooms. They had to be regular users of a PLD coupled with either a headphone or earphone for the previous six months. Participation was voluntary and students were allowed to
Results
After excluding eight subjects due to ear abnormalities and prior ear problems, 177 subjects with a mean (±standard deviation) age of 15.2 ± 1.1 years were included in this study. The majority of participants reported using more than one type of PLD. The most commonly used PLDs were mobile phones (51% of subjects), followed by mp3 players (36%), laptops (17%) and CD players (1%). The average duration of PLD usage for all subjects was 2.49 ± 1.48 years.
The mean measured listening level and
Discussion
With the increasing popularity of PLDs among teenagers, there is growing concern regarding the risk of hearing damage by improper use of these devices. Detailed population studies about the usage of current PLDs among adolescents and their possible impact on hearing, is limited. Prior studies involved small groups of PLD users3, 6, 19, 21, 22 and it is difficult to generalize their conclusions for other populations. The present study investigated the usage pattern of PLDs in a group of
Author statements
Acknowledgements
The authors wish to thank the students who participated in this study and the relevant school authorities for their cooperation and assistance during the study period.
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