Noise level is usually defined as the amplitude of various sounds that are occurring within a given area. In order to accurately measure levels of noise generated under specific circumstances, various sounds are evaluated and assigned what is known as a decibel level. Categorizing noise level into several different classes makes it possible to determine the potential for damage to the ears, as well as provide information that is helpful in selecting ear protection for those who must remain in the area for an extended period of time.
The typical noise level chart classifies various sounds based on five different categories. The first class is usually known as faint noise levels, and usually carries a range of no more than 30 decibels. These are considered to be completely safe and pose no threat at all to the ears. An example of a faint level would be a whispered exchange in a public library.
A second sound noise level classification is known as the moderate class. Like the faint category, moderate noises also pose no threat to the human ear, and are common. This level of noise is usually between 40 and 50 decibels, is often pleasant, and ideal for helping someone relax. A steady rain or a room that is more or less quiet are examples of a moderate sound level.
The third class is known as very loud. This class usually involves a range between 60 and 80 decibels. However, noises of this type are still considered acceptable, and do not pose any real threat to hearing capability. Typical street noise in a mid-sized city is an example of very loud noise, as is the ringing of an alarm clock, or a running vacuum cleaner.
An extremely loud noise level includes noises that do have some potential for causing damage to the ear, and has a range of 90 to 110 decibels. For example, loud machinery in a manufacturing plant can cause hearing loss, unless earplugs are used to muffle the sounds. Tools like a chain saw or large drills can also emit noises loud enough to cause damage, if the exposure is ongoing.
The most serious type of noise level is generally known as painful. This category is for noises that register over 120 decibels. Sounds in this category are capable of causing temporary or even permanent loss of hearing in one or both ears. The classic example of an event that creates sounds at this level is a rock and roll concert. Along with loud music, close proximity to a jet engine revving up for takeoff, an air-raid siren, or a jackhammer in use at a construction site are also good examples of noise levels capable of causing a loss of hearing ability.
In many situations where people are exposed to extremely loud or painful noise levels, the wearing of protective devices is considered to be absolutely necessary. Depending on the particular noise level, an individual may be required to wear simple earplugs that muffle the sound sufficiently to protect the ears. In more severe situations, ear protection that not only protects the ear canal but also encompasses the outer portion of the ear may be necessary to prevent any type of hearing damage.