Prevalence of hearing loss in college students: a meta-analysis.

Introduction: Hearing loss among college students, specifically noise-induced hearing loss (NIHL), appears to be increasing. This may be particularly challenging for this population as college students are required to listen to lectures in classrooms that may have suboptimal listening environments. College-aged musicians are at a particularly high risk due to repeated and extended exposure to loud noise. Therefore, the purpose of the current study was (1) to examine the prevalence of hearing loss in college students and (2) to emphasize the importance of detecting hearing loss at 6,000 Hz. Methods: A meta-analysis was conducted using the PRISMA model. The literature search yielded 8 studies (1,950 subjects) that tested hearing loss using an audiogram and Distortion Product Otoacoustic Emissions (DPOAEs). All studies used audiologic tests to detect hearing loss among college students between the ages of 17-35 years. Results: Results indicate that the prevalence of hearing loss in college students is 19%. In addition, the prevalence of hearing loss at 6,000 Hz is 85% among student musicians. For this meta-analysis, slight sensorineural hearing loss, or thresholds greater than 20 dB bilaterally or unilaterally, qualified as hearing loss. Discussion: Decreased hearing at 6,000 Hz may lead to an individual's inability to hear important environmental factors and high frequency speech sounds. College students without full auditory function at this frequency may have difficulties performing in class based on decreased attention, comprehension, and memory. Although students may not realize the influence of their 6,000 Hz hearing loss or be unaware of its presence, it could significantly change their likelihood to succeed in college. Therefore, implementing a hearing conservation program may be advised for colleges and universities to help prevent hearing loss in students, particularly for collegiate musicians. In addition, it may be beneficial to screen hearing in college students at 6,000 Hz for better detection of hearing loss overall.

Neuroendocrine and behavioral effects of embryonic exposure to endocrine disrupting chemicals in birds.

Endocrine disrupting chemicals (EDCs) exert hormone-like activity in vertebrates and exposure to these compounds may induce both short- and long-term deleterious effects including functional alterations that contribute to decreased reproduction and fitness. An overview of the effects of a number of EDCs, including androgenic and estrogenic compounds, will be considered. Many studies have been conducted in the precocial Japanese quail, which provides an excellent avian model for testing these compounds. Long-term impacts have also been studied by raising a subset of animals through maturation. The EDCs examined included estradiol, androgen active compounds, soy phytoestrogens, and atrazine. Effects on behavior and hypothalamic neuroendocrine systems were examined. All EDCs impaired reproduction, regardless of potential mechanism of action. Male sexual behavior proved to be a sensitive index of EDC exposure and embryonic exposure to a variety of EDCs consistently resulted in impaired male sexual behavior. Several hypothalamic neural systems proved to be EDC responsive, including arginine vasotocin (VT), catecholamines, and gonadotropin releasing hormone system (GnRH-I). Finally, EDCs are known to impact both the immune and thyroid systems; these effects are significant for assessing the overall impact of EDCs on the fitness of avian populations. Therefore, exposure to EDCs during embryonic development has consequences beyond impaired function of the reproductive axis. In conclusion, behavioral alterations have the advantage of revealing both direct and indirect effects of exposure to an EDC and in some cases can provide a valuable clue into functional deficits at different physiological levels.