NRR (Noise Reduction Rating)
Affiliate link — we may earn a commissionNRR is a number printed on hearing protection that tells you how many decibels it blocks under lab conditions. A rating of NRR 25 means the protector reduces noise by 25 dB in a controlled test. Real-world performance is lower. The OSHA derating formula subtracts 7 from the NRR, then divides by 2. So NRR 25 earplugs give you about 9 dB of effective reduction in the field. A circular saw produces 100 to 105 dB. A miter saw hits 104 to 110 dB. Sustained exposure above 85 dB damages hearing. You need hearing protection for every power tool louder than a vacuum cleaner.
Why It Matters
Hearing loss from tool noise is gradual and permanent. Most people skip ear protection because the saw "doesn't seem that loud." It is. Ten minutes with a miter saw above 100 dB starts causing damage. Get muffs or plugs rated NRR 22 or higher and wear them every time.