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Binaural calculation of Predicted Personal Attenuation Rating (P-PAR)
In addition to the individual evaluations of the Sonomax hearing protection devices (HPD) in Sonopass", a combined binaural calculation is provided to determine the combined predicted personal attenuation rating (P-PAR) for both ears. Generally, sound is perceived from the weakest hearing protector by frequency, but if hearing is substantially better in one ear, sound may be perceived from that side even if the hearing protector on that side is stronger.
Without Audiometric Data
Lacking audiometric data, Sonopass" defaults to assume hearing threshold levels (HTL) of 0dBHL (clinically normal hearing) in each ear. To simply the example, three octave bands are used instead of the seven (125Hz to 8kHz) used by Sonopass". In addition, a simpler method of calculating the overall P-PAR is used for demonstration purposes.
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Binaural P-PAR is calculated from the weakest attenuation or lowest value per frequency. In this instance the binaural P-PAR is lower than the P-PAR for either ear. Usually, one protector is stronger than the other at all frequencies, making the binaural P-PAR equal to the weaker protector.
With Audiometric Data
With audiometric data entered to Sonopass", further analysis is available. Generally, sound at any given frequency will be heard in the ear with the best protected threshold at that frequency. To calculate the binaural P-PAR, Sonopass" compares each protected threshold by frequency and selects the attenuation corresponding to the best protected threshold.
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| In this case, hearing levels in the better (left) ear determine the binaural P-PAR of 20. | |
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