To isolate ourselves from external sounds and noises, when traveling or on vehicles, people turn up the volume in their headphones or earphones. The limit for headphone/earphone volume for portable CD players has been set at 100 decibels. However, headphones sold individually can exceed this limit. To make the comparison clearer, here are the decibel levels of common sounds: 110-120 decibels is the sound power of a chainsaw in action or a jet in takeoff, while the sound of the human voice reaches 30-40 decibels. In addition, we must say that the decibel scale is a logarithmic scale so, for each increment of 10 decibels, the power of the sound is multiplied by 10. Moreover, studies show that the recommended intensity level should not exceed 85 decibels for a maximum of 8 hours during the day: at a level of 100 decibels, the damage could come after only 15 minutes.