This is most probably the PPE that will not be used as the damage is not apparent immediately. Noise induced hearing loss is normally not perceived until you get to 40-50 and by then it is too late.
When you are choosing the correct hearing protection, consider the level of noise that needs to be filtered out and what level of sound should be kept (eg: warning signals etc). To do this, you need to decide between simple ear plugs or ear defenders, earplugs generally offer more but ear defenders are generally more comfortable for long periods and easier to keep clean.
All ear protection should have a value for the amount of attenuation (sound reduction) it can provide, the single number rating (SNR) in Europe and Noise Reduction Rating (NRR) in US, this will be between 22 and 33 dB and for earplugs and ear is between 20 and 30 dB for ear defenders. However, combining the two will provide additional, and perhaps the best, protection. Keep in mind that a normal conversation is about 60 dB, and sounds of 85 dB and higher are harmful, depending on the length of exposure.
To figure out how much hearing protection your device offers here is a basic formula: ([SNR in dB] - 7) ÷ 2 = sound level you will experience. For example, the noise exposure from a saw is 100 dB and you are wearing a 33 dB hearing protection device. The noise level you would hear is 87 dB (33dB - 7 = 26 ... 26 ÷ 2 = 13 ... 100 - 13 = 87dB). Also, a product with a hearing protection level of 27 dB would deduct 10 decibels of sound from your environment (27dB - 7) ÷ 2 = 10.
You must understand what level of sound you are exposed to in order to calculate the minimum decibels of protection you need. You should aim to reduce sound to around 80 dB, with the upper limit being 87 dB. Most hearing protection has an eight-hour exposure rating.
If you use two devices (ear plugs and defenders) the you add 5 dB to the highest value and then use this in the noise reduction calculation.