Wednesday, January 28, 2004

Cardiovascular fitness and hearing

Well-known factors associated with hearing loss include aging, noise exposure, familial history and otologic disease. Several studies have also found a relationship between hypertension and hearing loss and arteriosclerosis and hearing loss. There appears to be a clear relationship between reduced blood supply to the inner ear and hearing loss.

There may also be a connection between a healthy blood supply to the inner ear and hearing.

Several studies have found a positive relationship between cardiovascular health and hearing thresholds.

Pure tone hearing thresholds were determined for 2, 3 and 4 kHz. (Hearing loss due to aging and other factors-usually appears first in the higher frequencies above 1 kHz.) Repeat hearing threshold measurements were taken 1 to 6 weeks later with good reliability.

As expected, hearing sensitivity was poorer in the over-50 age groups. Of interest in this study was the interaction between hearing levels and cardiovascular fitness for the older age groups.

While no significant differences were found in the under ­50 group, there was a positive relationship between cardiovascular fitness and hearing in the over-50 groups. In each of the three older groups, subjects in the high and medium cardiovascular fitness categories had better hearing than subjects in the low-fitness category. These differences were largest in the oldest group, with average differences of 10 dB and more between the low and high-fitness groups.

Consistently throughout the older groups, subjects with poor cardiovascular fitness had poorer thresholds than subjects with moderate and high fitness.

The authors suggest that a healthy cardiovascular system can minimize the effects of aging on hearing. They cite several studies that found improvements in hearing thresholds following extended cardiovascular exercise programs and conclude that results of the present study support the relevance of cardiovascular fitness in preserving hearing sensitivity over time.

— Dr. Andrew Waits