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Understanding EA18G contour map sound levels that harm you

A lot has been made of the Navy ” noise contour map”, but no one understands it. The Navy measures sound in what is called Ldn. This is an average of 365 days, 24 hours a day sound, it is one of the many valid ways to measure sound. Unfortunately (fortunately for the Navy) people don’t understand what the sound contour map really means. Many people know that noise over 84 dBA is harmful, (using another way of measuring), so they see the “noise contour map” showing 60 dBA, and they think, OK. no big deal, and the Navy counts on that!  Here is a chart by the EPA that very clearly shows that the figures on the noise contour map are harmful to this region’s health and welfare.

The W.H.O.states that the optimum noise figure is nothing over 50 dBA.

Subject: Safe Ldn levels

According the Environmental Protection Agency – EPA – the Day-Night Sound Levels – Ldn – and the Equivalent Sound Level – Leq – should not exceed certain limits to protect public health and welfare.

Values that should not be exceeded are indicated

Hearing

Leq (24) < 70 dBA

All areas

Outdoor activity interference and annoyance

Ldn < 55 dBA

Outdoors in residential areas and farms where people spend varying amounts of time in which quiet is a basis for use

Outdoor activity interference and annoyance

Leq (24) < 55 dBA

Outdoor areas where people spend limited time such as school yards playgrounds, etc.

Indoor activity interference and annoyance

Ldn < 45 dBA

Indoor residential areas

Indoor activity interference and annoyance

Leq (24) < 45 dBA

Indoor areas with human activities such as schools, etc.

Outdoor yearly Ldn levels protect public health and welfare if they do not exceed 55 dB in sensitive areas as residences, schools, hospitals, etc.

Inside buildings yearly Ldn levels protect public health and welfare if they do not exceed 45 dB.

Note! To protect against hearing damage, one’s 24-hour noise exposure at the ear should not exceed 70 dB.

Source: WHO, EPA, NPC Library: Protective Noise Levels

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