These High-Fidelity Earplugs from Vic Firth were designed to replicate the natural response of the ear canal so that sound is reproduced exactly as the ear would hear it, only quieter. Clarity of speech and richness of music are preserved rather than muffled. NRR is a value derived by mathematical formula that underestimates the effectiveness of flat attenuation earplugs. These earplugs have an NRR rating of 12 decibels. For musical applications, they are rated at ER20 so you can expect approximatley 20 dB of sound reduction across all frequencies in the real world. Heavy-duty neck cord and carrying case included.