In addition to causing hearing loss, noise exposure has also been associated with nonauditory health effects such as both transient and sustained hypertension, dyslipidemia and gastrointestinal symptoms. Using high-frequency hearing loss as a surrogate for prior noise exposure, we evaluated firefighters (FF, N = 77; age 32.6 ± 6.8SD, BMI 26.6 ± 3.9) and other first responders (OFR, N =49, age 36.6 ± 6.0; BMI 28.0 ± 3.6) who volunteered for an anti-terrorist team. Pooled results of their pure-tone audiograms showed that the mean HFHL, averaged over the noise-sensitive frequency bands of 2, 3 and 4 kiloHertz, was -12.9 ± 10.4 decibels (dBA) for the left ear and -10.4 ± 8.9, right ear. When corrected for presbycusis, the shift was -6.2 ± 10.5 in the worse ear. Blood pressure was measured at rest and again just prior to a maximal Bruce protocol treadmill electrocardiogram (GXT), and well as at maximal GXT exertion. (Table)
This lack of correlation between hearing loss and blood pressure does not support a role of repeated noise exposure as a contributor to hypertension, but we did not control for confounders such as family history, alcohol, tobacco or caffeine use, salt balance, or ototoxic medications. Nor do the above findings exclude the possibility of blood pressure elevations during off-shift hours, as some investigators have described.