1.  Prevalence and Audiological Factors Associated with Tinnitus in a College-Aged Population
Ishan Bhatt, PhD, CCC-A, FAAA
Communication Sciences and Disorders, Northern Arizona University
BACKGROUND
Research on the auditory lifestyle of college-aged young adults showed that almost 90% of young adults listened to music on a regular basis, with 26% listening to music for more than 3 hours per day, and 48% of them reporting that their typical listening level was at a high or near-to-maximum volume (Vogel et al., 2009 & Vogel et al., 2014).
Almost 50% were exposed to potentially harmful music, 44% used noisy equipment without hearing protection, and almost 29% of them worked in a noisy environment suggesting that the population might be susceptible to hearing loss and tinnitus (Breinbauer et al., 2012; Rawool & Colligon-Wayne, 2008).
Demographic and Environmental Factors Estimated by the Questionnaire
Gender was categorized as male and female.
Ethnicity was coded into non-Hispanic European American and other races (including multiracial).
Smoking was considered positive if a participant answered positively to: Have you ever smoked tobacco?
Re-occurring ear infection was considered positive if the participant answered positively to: Do you have a history of three or more ear infections?
Self-reported hearing loss was considered positive if the participant answered positively to: Do you have hearing loss?
Medical history was considered positive if the participant reported any systemic diseases.
Hyperacusis: It was assessed by three questions as follows: “Many everyday sounds are unbearably loud to me”; “Sounds that others believe are moderately loud are too loud for me”; and “I hear very soft sounds that others with normal hearing do not hear”. Participants were asked to rate agreement with these sentences on a 0 to 100 scale, where 0 = completely disagree and 100 = completely agree. Ratings of these questions were averaged to quantify hyperacusis on a 0 to 100 scale (Knudson et al., 2014).
Acoustic exposure was estimated via a self-report questionnaire developed by Megerson (2010). This survey has been validated to estimate overall acoustic exposure and has been utilized in previous research to quantify noise exposure in a collage-aged population (Megerson, 2010; Stamper & Johnson, 2015). It assessed nine specific known areas of high acoustic exposure: occupational noise, power tools, heavy equipment, commercial sporting or entertainment events, motorized vehicles, small aircraft, music instrument playing, music listening via personal earphones, and music listening via audio speakers. Noise exposure is quantified in LAeq8760hrs.
RESULTS (continued)
Subjects with high noise exposure, high hyperacusis score, positive history of smoking, European American ethnicity and female gender exhibited the highest odds of reporting any form of tinnitus.
Noise exposure, hyperacusis, self-reported hearing loss and ear infection were identified as major risk factors for chronic tinnitus.
The regression analysis further revealed hyperacusis, gender and smoking as major risk factors for acute tinnitus while noise, ethnicity and smoking were significant risk factors for subacute tinnitus.
Though noise exposure was identified as major risk factor for any form of tinnitus, only around 3% of variability in tinnitus was exclusively attributed to noise exposure (r=0.163, p= ).
Table: Coefficients of the multinomial logistic regression analysis. *p values less than 0.05, **p value less than 0.01, ***p value less than 0.001
Figure: Average noise exposure score among subjects with no tinnitus, subacute, acute and chronic tinnitus. Error bars: 95% CI
AIMES OF THE STUDY
To estimate the prevalence of chronic tinnitus, acute tinnitus and subacute tinnitus in a college-aged population (18-30 years).
To quantify the effects of demographic and environmental factors such as gender, ethnicity, self-reported hearing loss, re-occurring ear infection, smoking, health history, noise exposure and hyperacusis on chronic tinnitus.
METHODS
A cross-sectional survey was conducted among a population of college participants aged years from the Flagstaff campus of Norther Arizona University. The questionnaire was distributed in 20 randomly selected university classes. These classes included a total number of 867 students; out of this 678 participants filled out the survey resulting in the response rate of about 78%.
This survey included assessment of five areas: demographic details, medical and audiological history, hyperacusis, routine acoustic exposure, tinnitus and tinnitus-related distress in daily living.
The questions inquiring about tinnitus were adopted from the National Health and Nutrition Examination Survey (2010) (Center for Disease Control and Prevention, 2011). This section inquired about tinnitus with an opening question: “In the past 12 months, have you been bothered by ringing, roaring, or buzzing in your ears or head that lasts for 5 minutes or more?”. If the participant answered positively, then the follow-up question was: “How long have you been bothered by this ringing, roaring, or buzzing in your ears or head?”. Response choices for this question included: < 3 months/3 months to a year/1-4 years/5-9 years/≥ 10 years/Don’t know.
Operational definitions of chronic, acute and subacute tinnitus
The questions inquiring about tinnitus were adopted from the National Health and Nutrition Examination Survey (2010) (Center for Disease Control and Prevention, 2011).
Chronic tinnitus: bothersome tinnitus perception for ≥ 1 year.
Acute tinnitus: bothersome tinnitus perception for < 1 year.
Subacute tinnitus: at least 1 episode of tinnitus in entire life-span.
No tinnitus: no experience of tinnitus in entire life-span.
RESULTS
Figure: Prevalence of tinnitus in a college-aged population (N=678). Error bar indicates 95% CI.
DISCUSSION
Noise exposure, smoking, and re-occurring middle ear infection were identified as major environmental and health-related risk factors for tinnitus in college-aged young adults.
Though environmental and health-related factors explain a significant proportion of variability in tinnitus measurement, a large portion of variability in tinnitus measurement remained unexplained. It was hypothesized that genetic factors might explain this unexplained variability.
Importantly, systemic diseases and health-related risk factors did not show significant association with tinnitus in young adults. It suggests that a genetic association study in young adults might facilitate identification of important genetic variants underlying susceptibility to tinnitus.
Major references
Megerson SC. Development of a screening tool for identifying young people at risk for noise-induced hearing loss (Doctoral dissertation, University of Kansas).
Knudson IM, Shera CA, Melcher JR. Increased contralateral suppression of otoacoustic emissions indicates a hyperresponsive medial olivocochlear system in humans with tinnitus and hyperacusis. Journal of neurophysiology Dec 15;112(12):