Peace and quiet are important for mental and physical health.
Here are a few links to references:
(A 2005 study published in Lancet which showed that noise causes increased irritability, and a negative impact on cognitive development in school-aged children)
On a related note, the use of music players such as iPods can cause permanent hearing loss, particularly if people have the volume turned up very high. People are more likely to use higher iPod volumes if the background noise level is also high. Here are some links to information and evidence:
Also, the sound volume at a rock concert or a nightclub is sufficient to cause hearing damage, especially if this is an activity done regularly without hearing protection. I recommend using earplugs at rock concerts (yes, I'm serious!) Here is some evidence: