SNR 23 or SNR 33? How much attenuation you need
In short: 18 to 23 dB is enough for concerts, everyday life and sleep and keeps speech and music intelligible. You need 33 dB for machines and tools above 100 dB.
What the number means
SNR is the mean attenuation value of a hearing protector to EN 352. An SNR of 23 dB lowers the level at the ear by 23 dB in arithmetic terms, an SNR of 33 dB by 33 dB. 10 dB less is perceived as roughly half as loud. The value is a laboratory value; in practice, with an imperfect fit, the attenuation is somewhat lower.
Worked examples
| Situation | Level | with SNR 23 dB | with SNR 33 dB |
|---|---|---|---|
| Open-plan office | 65 dB | 42 dB | 32 dB |
| Concert, club | 100 to 110 dB | 77 to 87 dB | 67 to 77 dB |
| Angle grinder, circular saw | 100 to 105 dB | 77 to 87 dB | 67 to 72 dB |
| Jackhammer | 110 to 120 dB | 87 to 97 dB | 77 to 87 dB |
Target at the ear: below 80 dB(A) for continuous exposure, the lower exposure action value in EU Directive 2003/10/EC. At a concert, 18 to 23 dB leaves the level at around 80 to 90 dB, acceptable for an evening; on a building site only 33 dB will do. With the Music+ (SNR 18 dB) the values in the table are 5 dB higher.
Why not always 33 dB
More attenuation means less speech. With 33 dB you no longer understand colleagues without asking again, and at a concert the music sounds muffled. The Music+ is designed for 18 dB because its filter lowers all frequencies by a similar amount, which keeps the music clear. Too much attenuation also leads to the protector being taken off, and then it is useless.
Which product
SNR 18 dB: Music+ (concerts). SNR 22 dB: Sleep+ (sleep). SNR 23 dB: Strong+ (everyday life, two sizes), Women+ (small ear canals). SNR 24 dB: MINI+ (babies). SNR 27 dB: Soft+ (mouldable). SNR 28 dB: Kiddies (children). SNR 29 dB: Kids+ (children's plugs). SNR 33 dB: Work+ (work). Basics on the page What is SNR?, levels of typical situations in the guide Noise sources and their loudness.
Frequently asked questions
Does the SNR apply to all frequencies?
No, it is a mean value. The H, M and L values give the attenuation for high, medium and low tones. For the Kiddies, for example, H 33, M 25, L 18 dB.
Is SNR 23 dB enough for motorcycling?
Wind noise reaches 90 to 100 dB at 100 km/h. With 23 dB the level stays above 70 dB on longer rides. For long distances the Soft+ with 27 dB is the better choice, for short ones the Strong+.
Can I wear two plugs on top of each other?
No. For more attenuation, plugs are combined with ear muffs; the gain is around 5 dB.
What is the difference between SNR and NRR?
NRR is the US value to ANSI, SNR the European one to EN 352. The figures are not directly comparable; NRR is usually a few dB lower for the same product.