Keywords
adolescents - college students - noise - secondhand smoke - tinnitus
Introduction
Tinnitus is most often described as a ringing or buzzing in one's ears without the
presence of external auditory stimulation. It can create difficulties with concentration,
inability to hear sounds of interest, and frustration for those experiencing it. It
is typically associated with older adults, with approximately 13–33% of individuals
>60 years reporting tinnitus (McCormack et al, 2016[12]). However, recent studies indicated young adults and teenagers may be experiencing
tinnitus in higher numbers than previously believed. For example, Muhr and Rosenhall
(2010)[14] reported that 23% of college-aged individuals have experienced tinnitus, and Bhatt
(2017)[2] reported that 59.3% of college-aged individuals had experienced tinnitus at least
once in their lifetime. These reports indicated prevalence discrepancies, and it may
be unclear which age group typically experiences more tinnitus. Although tinnitus
(a symptom) is more commonly reported in those with audiometric hearing loss (Davis
and El Refaie, 2000[4]), it does occur in individuals with normal hearing thresholds. For example, one
study on participants aged 12–19 years (n = 4,396) found that 23.6% of those who reported
tinnitus also had some hearing loss, but 76.4% of those who reported tinnitus had
normal hearing thresholds (Mahboubi et al, 2013[10]). Thus, tinnitus in the presence of normal hearing is not unexpected among adolescents.
In addition, the interaction of age with gender influences tinnitus prevalence; in
children, females appear to have a higher likelihood of developing tinnitus (Lee and
Kim, 2018[9]) but in adults, males have a higher prevalence of tinnitus (McCormack et al, 2016[12]).
The etiology of tinnitus is often unknown (Stouffer and Tyler, 1990[20]). Tinnitus can occur when microscopic outer hair cells in the cochlea are damaged
leading to abnormal movement with electrical impulses sent to the brain that are perceived
as noise or tinnitus. Several other variables, including age, gender, socioeconomic
status, occupation, smoking, and alcohol, are related to the prevalence of tinnitus
(Davis and El Refaie, 2000[4]). In addition, other factors, including excessive noise, have been studied thoroughly
and are well known to be associated with tinnitus (Moore et al, 2016;[13] Bhatt, 2017[2]).
Exposure to Noise
Permanent damage due to excessive noise exposure can be hazardous for college students
who are often exposed to recreational noise, more often than older generations. Students
can be exposed to excessive noise from workplace settings, music at concerts, in bars,
or from personal music players. Mahboubi et al (2013)[10] studied the association between tinnitus and noise (music) exposure in normal hearing
adolescents aged 12–19 years by examining the odds ratio (OR). Their results indicated
that adolescents who were exposed to recreational noise had a significantly higher
odds ofreporting chronic tinnitus (OR: 2.08; 95% confidence interval [CI]: 1.353.18)
or overall tinnitus (OR: 2.17; 95% CI: 1.30-3.62). In a Swedish study of healthy young
men (n = 839) aged 19–22 years, 23% of participants reported experiencing tinnitus
(Muhr and Rosenhall, 2010[14]). In addition, participants who reported playing loud music had a significantly
higher prevalence of tinnitus compared with the control group (p ≤ 0.001), and one in ten participants reported experiencing tinnitus “often” after
exposure to noise. In a study of college students (n = 238), Rawool and Colligon-Wayne
(2008)[19] reported that young adults' attitudes toward noise could have negative impacts on
their hearing because 75% of students surveyed knew that noise could cause hearing
loss, but 50% still knowingly exposed themselves to dangerous noise levels. This perceived
invulnerability was evidenced by the fact that 76% of college students surveyed believed
they would not lose their hearing until they were older, and 58% believed that they
did not need to worry about the ringing in their ears as long as it was temporary.
Exposure to Secondhand Smoke (SHS)
The effect of cigarette smoking on the auditory system has been recently documented
(c.f., Ramkissoon and Chambers, 2008;[18] Harkrider et al, 2001;[6] Bhatt, 2017[2]). Effects of SHS exposure, however, is less studied. SHS exposure or passive smoking
occurs when a person involuntarily inhales smoke from cigarettes typically being smoked
by another person. Cigarette smoke has >4,000 chemicals and 50 carcinogens, and exposure
to SHS is associated with a plethora of health problems, including heart disease,
lung cancer, and respiratory infections (National Cancer Institute, 1997[15]). A study using data from the National Health and Nutrition Examination Survey (2013-2014
cycle) found that 58 million (25%) US nonsmokers were exposed to SHS (Tsai et al,
2018[21]). In addition, SHS was recently associated with hearing loss (Fabry et al, 2011;[5] Lalwani et al, 2011[8]). Given that 29 million US adults experience hearing loss, SHS could well be a primary
or contributory cause of hearing loss nationally.
College students are particularly vulnerable to SHS exposure because of their socialization
patterns on campus, at bars/clubs, or in homes and cars with friends. In fact, as
many as 83% of students reported at least one exposure to SHS in the last seven days
(Wolfson et al, 2009[22]). Specifically, 65% of SHS-exposed students reported exposure at a restaurant/bar,
55% in the same room with a smoker, and 38% in a car with a smoker.
One study examined SHS in former smokers and never smokers aged 20–65 years and found
that 46.6% of SHS-exposed former smokers along with 26.6% of never smokers experienced high-frequency hearing loss (Fabry et al, 2011[5]). They reported a significant positive association between SHS exposure and hearing
loss at low/mid frequency levels for both former and never smoker groups. In former
smokers, SHS exposure and high-frequency hearing loss were significantly and positively
related (Fabry et al, 2011[5]). These results were some of the first to connect SHS exposure to hearing loss.
More recently, Chang et al (2015)[3] examined smoking effects on hearing loss in Korean adults aged 19–80; one group
was “passive smokers,” defined as people who had never smoked but were exposed to
SHS daily. These passive smokers had worsened pure-tone hearing thresholds than nonsmokers
without SHS exposure.
Lalwani et al (2011)[8] examined hearing status in 1,533 adolescents aged 12–19 years, with 49% of the sample
having SHS exposure. They defined hearing loss as pure-tone thresholds >15 dB and
categorized hearing loss by laterality and frequency range involved. They found that
prevalence of sensorineural hearing loss was higher in adolescents with SHS exposure
compared with unexposed individuals, for all hearing loss categories. In particular,
SHS-exposed adolescents had significantly elevated hearing thresholds for unilateral
low frequency hearing loss (p = 0.03) and bilateral high-frequency hearing loss (p = 0.04). The relationship between SHS exposure and hearing thresholds at individual
frequencies was also examined. Thresholds in SHS-exposed adolescents were significantly
elevated at 2000, 3000, and 4000 Hz compared with the nonexposed group. Notably, these
statistically significant differences in hearing thresholds were on the order of 1–3 dB;
this has minimal clinical significance.
The impact of SHS exposure on auditory function was further explored with pure-tone
audiometry and evoked potential testing in college students aged 18–23 (Ramkissoon
and Batavia, 2018[17]). Their results revealed that although all participants had normal hearing thresholds,
central auditory system functioning was affected in students exposed to SHS. Specifically,
young adults with SHS exposure had delayed wave Pb latency (auditory middle latency
response) and decreased wave V/I amplitude ratio (auditory brainstem response) compared
with individuals who were unexposed to SHS. These findings suggested a possible toxicity
effect of SHS exposure on the central auditory system.
Mahboubi et al (2013)[10] evaluated the occurrence of tinnitus in 4,396 adolescents (12-19 years); of whom,
19.4% were exposed to SHS. Results revealed that SHS-exposed adolescents were almost
twice as likely (OR = 1.95, [CI: 1.23-3.11]) to develop overall tinnitus and 1.76
(OR, CI: 1.00-3.10) times more likely to develop chronic tinnitus. Another study surveyed
Serbian secondary school students aged 14–20 years (n = 771) regarding tinnitus, SHS
exposure, and noise exposure (Marmut et al, 2014[11]). In total, 12.8% of students reported tinnitus, with girls reporting it more frequently
than boys. About 50% of students reported were being exposed to SHS. The Spearman's
coefficient results revealed a positive significant correlation between tinnitus and
smoking (p = 0.196), tinnitus and SHS exposure (ρ = 0.125), and daily duration of SHS exposure
and tinnitus (ρ = 0.224) in boys. In girls, there was a significant positive relationship
(ρ = 0.110) between tinnitus and daily time spent indoors being exposed to SHS. Multivariate
logistic regression analysis revealed a significant independent effect of daily duration
of SHS exposure to tinnitus (p = 0.009) in girls. This means that daily duration of SHS exposure predicted tinnitus
occurrence in girls. This study strongly suggested that SHS exposure and tinnitus
may be related.
Purpose of the Present Investigation
The goal of the current study was to examine how two environmental factors, SHS exposure
and noise exposure, related to the occurrence of tinnitus in normal hearing US college
students and adolescents. This study focused on a younger population to examine, in
greater depth, the effects of SHS and noise on tinnitus occurrence because most previous
research was conducted in adults, particularly older, hearing-impaired individuals.
Although a few past studies have connected SHS exposure to hearing loss, there is
limited information relating SHS to tinnitus. This is also the first known study to
examine possible interactions between SHS exposure and noise exposure as it impacts
tinnitus occurrence. The results may be useful for public health initiatives promoting
hearing health, particularly in college students and adolescents.
Research Questions
-
Is exposure to SHS related to tinnitus occurrence in college students and adolescents?
-
Is exposure to noise related to tinnitus occurrence in college students and adolescents?
-
Are there interactions between SHS exposure and noise exposure as they influence tinnitus
occurrence in college students and adolescents?
Methods
Study Design
This study used a nonexperimental cross-sectional design. Data were gathered from
an archived survey study approved by the Institutional Review Board protocol #12-091.
The original survey included questions about participants' biographical information,
any hearing/ communication difficulties, exposure to SHS (e.g., number of smokers
in the home), exposure to loud noises (e.g., type of noise environment), and tinnitus
(e.g., which ear and how often). However, the current study approved under Institutional
Review Board protocol #17-200 analyzed a subset of the data. Three specific yes/no
questions about the occurrence of noise exposure (Have you been exposed to loud noises on a regular basis?), SHS exposure (Do you live in a home where one or more people smoke tobacco products?), and tinnitus (Do you experience tinnitus [noise in your ear like ringing or buzzing]?) were analyzed.
Participants
A total of 265 surveys were available for this study (171 college students and 94
adolescents). Forty-three surveys were excluded from data analysis for reasons such
as current smoking, age, medications linked to tinnitus, missing data, and hearing
loss. Of the remaining 222 participants, 160 were female, eighty were high school
students (aged 14–17 years), and 142 were college students (aged 18–30 years). All
participants were in overall good health with no reported hearing/communication difficulties.
The mean age was 18 years overall (range: 14–30 years, SD = 2.73); 15 years for adolescents
and 19 years for college students.
Procedure
Survey responses to the three selected questions for n = 222 participants were entered
into a spreadsheet.
Participants were assigned an ID number, and other information such as age, gender,
smoking behavior, and reported communication difficulties were also entered into the
spreadsheet. Original survey responses for SHS exposure at home was divided into two
categories-“SHS in the home” and “SHS near the home.” For analysis purposes, these
two responses were collapsed into one category titled “SHS-home” and a “yes” response
to either question was accepted. Data were transferred into SPSS version 22 (IBM Corp.,
Armonk, NY) for statistical analysis.
Results
The current investigation examined the relationship between reported SHS exposure,
noise exposure, and tinnitus occurrence in college students and adolescents. Of 222
participants, 31% (n = 68) reported SHS exposure, 41% (n = 91) reported noise exposure,
and 40% (n = 89) reported experiencing tinnitus.
The first statistical analysis conducted was a binary logistic regression to examine
the relationship of SHS exposure, noise exposure, gender, and age on tinnitus occurrence.
The results from the regression analysis are shown in [Table 1]. There was a significant main effect on noise exposure (p = 0.004) and a significant interaction effect (SHS/Noise) on tinnitus (p = 0.001). Gender was also a significant factor in predicting tinnitus (p = 0.017). There was no main effect of SHS exposure nor age on tinnitus occurrence.
The slope of −2.074 for the SHS/noise interaction variable had the highest predictive
value in this analysis, that is, the SHS/noise interaction was the most likely independent
variable to produce lower levels of tinnitus. The current standard error range of
0.05-0.6 indicated that there was less error in the measurement.
Table 1
Variables in the Regression Equation
|
Factors
|
β
|
Standard Error
|
Significance
|
|
Gender
|
0.800
|
0.334
|
0.017[*]
|
|
Age
|
0.005
|
0.054
|
0.929
|
|
SHS
|
0.557
|
0.419
|
0.183
|
|
Noise
|
1.020
|
0.358
|
0.004[**]
|
|
Interaction of SHS and noise
|
−2.074
|
0.647
|
0.001[**]
|
|
Constant
|
−1.369
|
1.076
|
0.254
|
*
p < 0.05.
**
p < 0.01.
A chi-square analysis conducted to probe the gender effect revealed that females were
more likely than males to experience tinnitus, with 45.1% of females reporting tinnitus
and only 27.7% of males reporting tinnitus. Furthermore, chi-square analyses were
conducted to examine the significant interaction effect (SHS by noise) using the “split
file” feature in SPSS. The results are shown in [Table 2], which categorizes participants by noise exposure, that is, “no noise” and “noise-exposed.”
Within these two noise categories, participants were further divided by SHS exposure,
and the resultant number of participants per category is shown with the percent of
the total sample in parenthesis. The results indicated statistical significance (p = 0.001) for the group of individuals with noise exposure but not for individuals
without noise exposure. In the noise-exposed group, individuals who also reported
SHS exposure had a lower occurrence of tinnitus (23.6%). By contrast, the noise-exposed
individuals without SHS exposure had a higher prevalence of tinnitus (57.9%). An additional
chi-square follow-up analysis was conducted to examine the main effect of noise; this
analysis did not reveal significance (p = 0.199). Chi-square analysis for the SHS exposure variable was also not significant.
Table 2
Tinnitus in Individuals Based on Noise Exposure and SHS Exposure
|
Noise Group
|
|
n (%)
|
Tinnitus: n (%)
|
Significance
|
|
Absent
|
Present
|
|
No noise
|
No SHS
|
97 (44%)
|
64 (66.0%)
|
33 (34.0%)
|
0.199
|
|
SHS-exposed
|
34 (14%)
|
19 (55.9%)
|
15 (44.1%)
|
|
Noise-exposed
|
No SHS
|
57 (26%)
|
24 (42.1%)
|
33 (57.9%)
|
0.001[*]
|
|
SHS-exposed
|
34 (15%)
|
26 (76.4%)
|
8 (23.6%)
|
* Fisher's exact test used for significance; n = 222.
Correlation analysis was conducted in SPSS to examine the relationship between tinnitus
and SHS exposure, noise exposure, and age. The results in [Table 3] indicate that noise exposure was significantly correlated with age; this was a low
negative correlation. No other bivariate correlations were significant.
Table 3
Correlations between Variables of Interest
|
SHS Exposure
|
Noise Exposure
|
Tinnitus
|
Age
|
|
SHS exposure
|
1
|
0.122
|
−0.085
|
0.064
|
|
Noise exposure
|
0.122
|
1
|
0.084
|
−0.244[**]
|
|
Tinnitus
|
−0.085
|
0.084
|
1
|
−0.028
|
|
Age
|
0.064
|
−0.244[**]
|
−0.028
|
1
|
** Correlation is significant at the 0.01 level (two-tailed).
Discussion
The current study hypothesized that noise exposure and SHS exposure would each predict
reported tinnitus in college students and adolescents. In addition, it was hypothesized
that individuals who experienced a combination of SHS exposure and noise exposure
would be more likely to report an even higher occurrence of tinnitus. The current
results did not support all hypotheses and revealed some unexpected findings. The
discrepancies found in the current results compared with previous studies indicate
that further research on current study variables as related to tinnitus should be
conducted.
The hypothesis related to noise exposure was not supported. The initial regression
analysis showed that noise exposure was a significant factor in predicting tinnitus.
However, a follow-up chi-square test for significance indicated the relationship between
tinnitus and noise exposure was not significant. This result differed from past studies.
For example, Mahboubi et al (2013)[10] reported that tinnitus was exacerbated by exposure to excessive noise in adolescents,
12–19 years, and Hinalaf et al (2017)[7] indicated that adolescents with higher levels of general music exposure had significantly
higher reported tinnitus (72.41%). The current study results might have differed from
these past studies because of a smaller convenience sample and different test procedures
used.
The current results indicated that SHS exposure was not significant in predicting
tinnitus, a finding which differed from previous studies. For example, Marmut et al
(2014)[11] found that tinnitus occurrence was correlated with daily duration of SHS exposure
in boys and girls aged 15–19 years and also with SHS exposure overall, in boys only.
Similarly, Mahboubi et al (2013)[10] found that adolescents exposed to SHS were almost twice as likely to develop tinnitus
and 1.76 times more likely to develop chronic tinnitus. However, the current study
included design elements that might explain our findings being different. Specifically,
there was a smaller proportion of males (23%) in the current than in the past studies
(36-43%), and the current study included both adolescent and young adult participants
compared with Marmut and Mahboubi who examined the link between SHS exposure and tinnitus
occurrence in adolescents only. In addition, other studies reported a link between
SHS exposure and sensorineural hearing loss in adolescents (Lalwani et al, 2011[8]) as well as the SHS exposure and central auditory function (auditory brainstem response,
auditory middle latency response) in young adults (Ramkissoon and Batavia, 2018[17]). The lack of relationship between SHS exposure and tinnitus found in the current
results compared with these previous studies indicates the need for further research
to better understand this variable.
Perhaps, the most interesting finding in the current study was related to the interaction
of SHS exposure and noise exposure on tinnitus occurrence. The results showed that
individuals who reported exposure to both SHS and noise had the lowest tinnitus prevalence
of 23% (refer to [Table 2]). This was an unexpected result. The other known studies that evaluated both SHS
and noise exposure as related to tinnitus were reported by Marmut et al (2014)[11] and Mahboubi et al (2013)[10]. However, in both of those studies, each variable was analyzed separately, and the
authors did not examine any interaction effect of SHS and noise in the same participant.
Thus, there are no known past results to compare the current interaction effect with.
We had anticipated a cumulative effect of SHS and noise exposure on tinnitus occurrence,
but instead the lower occurrence of tinnitus in these individuals warrants further
investigation.
A few other current results are interesting. First, the current prevalence of tinnitus
in college students and adolescents was 40%, much higher than past reports (Davis
and El Refaie, 2000;[4] Muhr and Rosenhall, 2010;[14] Moore et al, 2016[13]) but similar to recent reports (Bhatt, 2017;[2] Hinalaf et al, 2017[7]) where 64% and 59.3% of college students reported occurrence of tinnitus, respectively.
Overall, although the current results and these past studies did not all have the
same design, the reported tinnitus prevalence of 40–64% indicates that many younger
adults and adolescents appear to be susceptible to tinnitus than previously believed.
Another interesting finding in this study was the gender effect, with female gender
being a significant factor in predicting tinnitus. A higher percentage of females
reported tinnitus than males, which is similar to other studies with adolescents where
female gender was a risk factor for tinnitus (Mahboubi et al, 2013;[10] Marmut et al, 2014;[11] Park et al, 2014[16]). Third, the current result (see [Table 2]) indicated that among noise-exposed individuals (n = 91), the highest occurrence
of tinnitus (n = 33; 57.9%) occurred in individuals with no reported SHS exposure.
This implied that having noise exposure without SHS exposure increases the chance
of tinnitus. Perhaps, noise exposure is the most important predictor of tinnitus occurrence
as shown previously (Muhr and Rosenhall, 2010;[14] Mahboubi et al, 2013;[10] Marmut et al, 2014;[11] Lee and Kim, 2018[9]). Overall, however, the specific implications of this result are unclear and need
further exploration. Finally, the significant negative correlation (r = -0.244) between noise and age indicated that as age increased, the amount of noise
exposure decreased. For the current sample, it may be assumed based on the mean age
of 18.2 years (SD = 2.7) that individuals aged 21–30 years had less noise exposure,
possibly because of changes in recreational and occupational environments, than those
aged 14–20 years. This has potentially important clinical and counseling implications.
An additional important application of the current results is related to educating
adolescents and young adults about how noise is significantly linked to tinnitus.
A limitation of this study is that tinnitus occurrence was evaluated based on self-reported
data without corroboration through clinical assessment. For the noise factor, our
survey question recruited individuals with regular, consistent exposure to loud noise
but did not specify the type, source, or specific duration of the noise exposure.
Also, participants who reported any exposure to SHS, irrespective of SHS exposure
duration, were included which may have influenced the results. Furthermore, SHS exposure
was not classified by cotinine level, a more objective measure. However, Avila-Tang
et al (2013)[1] indicated that often even known SHS-exposed individuals tested negative for SHS
exposure on objective measures. Follow-up research currently ongoing in our laboratory
is examining details about noise and SHS exposure as it influences tinnitus occurrence
and reported hearing difficulties.
Conclusion
The current study suggests there is a higher-than-expected report of tinnitus incidence
in adolescents and young adults. This result supports other recent studies showing
similar high tinnitus incidence in college students. The relationship between tinnitus
occurrence and a combined exposure to noise and SHS revealed a unique effect. Specifically,
noise-exposed individuals without SHS exposure had the highest tinnitus prevalence.
This relationship needs further investigation.
Abbreviations
CI:
confidence interval
OR:
odds ratio
SHS:
secondhand smoke
