Casella CEL-352 dBadge Manuel d'instructions télécharger pdf (Page 38)

Casella CEL-35X dBadge Users Handbook – Page 38

Where PNR is the predicted noise level reduction provided by the

hearing protection. For example, if from the CEL-352 dBadge

‘Plus’ the values were:

Ceq

102.4dB L

Aeq

98.6dB

Therefore, as the L

Ceq

– L

Aeq

value is greater than 2:

PNR = M – x (L

Ceq

– L

Aeq

– 2)

From the example of the hearing protector mentioned above:

PNR = 25 – x (102.4

– 98.6

– 2)

PNR = 25 – 1 x 1.8

PNR = 25 – 1.8

PNR = 23.2dB

The A-weighted SPL at the ear = L

Aeq

– PNR

The A-weighted SPL at the ear = 98.6 – 23.2 = 75.4 = 75dB(A)*

*Note: some countries assume that ‘real world factors’ will

effectively reduce the effectiveness of hearing protection. For

example, in the UK a further standard 4dB is taken off the PNR, so

in this case the value at the ear would be 79dB(A).

(25-17)

(M-L)

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Casella CEL-352 dBadge Manuel d'instructions Page 38