How Do You Read a DBA Chart?


Quick Answer

Read a dBA chart by finding the appropriate noise source or a similarly loud source on the chart and then finding the dBA value associated with that noise source on the same row. These charts list values in adjusted decibel units. Decibels are degrees of sound intensity as measured by a sensitive electronic instrument, while adjusted decibels pass sounds through an audio filter that more accurately reflects how an actual human ear registers them.

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Full Answer

A dBA chart is a useful for determining if exposure to certain sounds is safe or potentially harmful. Generally, exposure to any noise of less than 85 dBA is same for an unlimited amount of time. Exposure to any sound of more than 140 dBA requires hearing protection to avoid potential hearing loss.

A helpful chart used along with a dBA chart is a dBA exposure chart. These charts list maximum daily exposure times for different noise levels. For example, the maximum daily time a person should have unprotected exposure to 112 dBA, roughly the noise level of a live rock band, is only 56 seconds. The times on exposure charts represent the total daily amount of safe noise exposure, meaning that if a person takes out his ear plugs for one song at a rock concert, he should avoid exposure to any sound louder than 85 dBA for the entire remainder of that day.

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