Oz Pax, That info should be of benefit to all of us, thanks for that.
Interestingly, the 85dB is a background noise level; to hear speech, either through the headset or directly would require modulation at around 20 -30 db on top of background levels. Therefore, you would be receiving in excess of 105dB into your ear. The first sign of damage would be diminishing high tone response as the high frequency scilla are closer to the entrance of the middle ear than the lower freq bits.