Do high-NRR muffs really block 34-37 dB?

This is contested. Lab-tested user reports on Amazon and on the r/hyperacusis community note that OSHA-adjusted NRR for the highest-rated muffs lands closer to 31-34 dB rather than the advertised 37 dB. Multiple high-NRR products from different brands cluster at very similar real-world attenuation.