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Use of Telephones in Noisy Areas

Satisfactory, difficult and impossible noise levels for telephone use in noisy areas.

Background noise interferes with telephone conversations, and

conditions are satisfactory at levels less than 65 SIL (dB) (approx. 72 dBA)
conditions are difficult at levels in the range 65 - 80 SIL (dB) (approx. 72 - 87 dBA)
conditions are impossible at levels above 80 SIL (dB) (approx. 87 dBA)

Logarithmic unit used to describe ratios of signal levels - like power or intensity - to a reference level.

Comparing Noise Criterion (NC, NCB, RNC) to Noise Rating (NR) and dB(A).

Background noise frequencies that interferes with speech.

Sound power from sources like fans, jet engines, cars, humans and more.

Sound Pressure is the force of sound on a surface perpendicular to the propagation of sound.