Mass transit commuters are regularly exposed to excessive noise levels. The use of personal listening devices (PLDs) adds further stress on the auditory system as commuters listen at high volume levels to mask the background noise encountered during their daily commute. In fact, studies show that PLD users increase the volume of their devices when in areas with high background noise, thereby creating further risk of noise-induced hearing loss (NIHL; Ear Hear. 2007;28:290 http://bit.ly/2mJETVb).
Mass transit systems have highly reverberant sound fields and levels of noise (Am J Public Health. 2009;99:1393 http://bit.ly/2nkjkw5;Environ Sci Technol. 2012;46:500 http://bit.ly/2n6yCEf;J Acoust Soc of Amer. 2012;132:1407 http://asa.scitation.org/doi/abs/10.1121/1.4740472). Dosimeter analysis of a representative sample of mass transit systems, including subways, buses, ferries, tramways, and commuter railways, in New York City (NYC) found that sounds measured in all transit types exceeded 70 dBA, posing a risk of NIHL (Am J Public Health. 2009 http://bit.ly/2nkjkw5). The highest noise levels (>80 dBA) were recorded in subway cars and platforms (Am J Public Health. 2009 http://bit.ly/2nkjkw5). In a survey of 4,436 NYC adult commuters, Neitzel, et al., determined that the noise exposure of 90 percent of the transit users exceeded the recommended 70 dBA annual exposure limit (Environ Sci Technol. 2012 http://bit.ly/2n6yCEf). Furthermore, over 70 percent of transit users reported using PLDs, and exceeded the average annual listening time of non-users by almost 150 hours.
NIHL occurs in stages across several years. As such, its effects often go unnoticed. Overexposure to high levels of noise causes hearing loss. Next to age-related hearing loss, NIHL is the most commonly acquired hearing impairment. The risk of developing NIHL increases with continuous exposure to high-level noise. NIHL initially affects hearing frequencies between 3.0-6.0 kHz. The condition is often detected when the damage has already spread to other frequencies and affected the person's speech intelligibility; unfortunately, the hearing loss is irreversible by this stage. Untreated hearing loss is also associated with non-auditory issues such as heart disease, high blood pressure, sleep disturbance, psychosocial annoyance, and cognitive decline (e.g., dementia; Int J Audiol. 2003;42 Suppl 2:2S17 http://bit.ly/2tSbSM6).
Significant research has been done on NIHL risk factors and safe listening practices with PLDs, but how well has this information been translated for the public? This survey investigated the general awareness of NYC mass transit commuters about NIHL and PLD use.
This research study was approved by the Internal Review Boards of Adelphi and St. John's Universities. An online survey was sent via email to 500 participants over 18 years of age, from December 2015 to March 2016. The survey was directed towards individuals who frequently commute on the NYC subway, bus, or commuter rail systems. The survey had two sections: part 1 on demographics with questions about gender and transportation modes; and part 2 on NIHL awareness with questions on NIHL prevention, risk factors, consequences and public conservation efforts, and perceived PLD use (see Figs. 1 and 2).
A total of 296 participants aged 18 years and older completed the online survey; 69 were men (23.3%) and 227 (76.7%) were women. Respondents reported taking various methods of public transportation, including commuter rail (40.5%), subway (51.4%), and bus (8.1%). Most respondents (60.8%) reported taking public transportation five days a week, with 56.1 percent commuting for one hour or more on a typical day. Nearly 10 percent of respondents reported having a known hearing loss, 73 percent reported no known hearing loss, and 17.2 percent were unsure (Fig. 1).
Most respondents (83.1%) indicated listening to music through a PLD with earphones or headphones for an average of two or more hours per week (Fig. 1). Majority of respondents used their PLDs when commuting (73.6%), and recognized that the noise on the subway and trains reach sound levels that can be harmful to their hearing (78.8%; Fig. 2). However, only 29.4 percent admitted to listening to their devices at dangerous volume levels, and most did not recognize the adverse effects of this listening practice. For example, only 19.7 percent of respondents strongly agreed or agreed that using the device at the 90 percent volume setting is safe when listening for less than 20 minutes (J Am Acad Audiol. 2011;22:663 http://bit.ly/2urja6x). Most (95.6%) were aware that hearing loss affects people of all ages and demographics. More than half knew that hearing loss caused by noise exposure is preventable (75.6%) and that tinnitus can be caused by excessive noise exposure (64.6%).
Most respondents (70.1%) have thought about the impact of PLDs and environmental noise on their hearing, and many (60.3%) were concerned about developing hearing loss in the future. However, only a few recognized the serious health consequences of untreated hearing loss. For example, only 16.0 percent strongly agreed or agreed that untreated hearing loss is linked to cognitive decline such as dementia. Notably, only 23.3 percent of respondents have seen public service announcements (PSAs) on the effects of hearing loss or the dangers of excessive noise exposure.
Studies have shown that the maximum output levels of PLD earphones measure over 100 dBA (A-weighted decibels) and that long-term use of PLDs at excessive volume levels may harm the auditory system (Laryngoscope. 2012;122:2549 http://bit.ly/2mWvHNY). In particular, listening to high-intensity, amplified music through PLDs can contribute to potential NIHL due to the signal's low-frequency spectral composition and non-steady nature and the tendency or preference of users to listen to music at higher volumes. Notably, even improvements in PLD technology, such as extended battery life, could result in longer and uninterrupted listening, further contributing to possible NIHL. In an evaluation of the listening practices, PLD use, and auditory symptoms of 282 young adults, Sulaiman and colleagues found more reports of tinnitus and hearing difficulty among PLD users listening at volumes ≥75 dBA (J Int Adv Otol. 2015;11:104 http://bit.ly/2n6pqzu). In addition, significantly higher mean hearing thresholds at extended high frequencies of 9.0–1.6 kHz were found among those using PLDs for ≥4 years at volumes ≥75 dBA.
This study shows that mass transit commuters in NYC do not completely understand the consequences of hearing loss and the proper use of PLDs. While research supports the effectiveness of using hearing aid imageries in PSAs to encourage safe listening, only a few commuters attested to seeing related PSAs (Am J Audiol. 2016;25:332 http://bit.ly/2mGfjz0). Ultimately, this study indicates the need for hearing health professionals to do a better job at educating the public about the risks of NIHL and safe listening habits.