While music can be a powerful motivator—as you start to lose steam, the music swells and you feel energized to push through the last little bit of your workout. Many exercise classes, including spin classes and aerobic classes, use music as a motivator in much the same way.  But researchers from Harvard have found that these classes are consistently above the level considered safe for hearing.

More and more, noise-induced hearing loss is being accepted as a universal - though preventable - health problem.

In fact, hearing loss is the third most common chronic health problem in the United States (behind diabetes and cancer), with one in four adults showing signs of noise-induced hearing loss.