SNR Method Hearing Protection Calculator
The SNR method is the simplest way to estimate hearing protection at the ear. Enter the protector’s Single Number Rating and the C-weighted workplace noise level. The calculator returns the protected level at the ear and an HSE protection rating, used to check protection against the action and limit values in the Control of Noise at Work Regulations 2005.
Note: LCeq is the time-averaged C-weighted level. Do not confuse it with the peak C-weighted level (LCpeak), which is usually 20 dB or more higher.
Enter values to see the result
Add the SNR value for the protector and the C-weighted workplace noise level.
How to Use This Calculator
Enter the SNR (Single Number Rating) from the protector’s datasheet and the C-weighted noise level (LCeq) from a workplace noise survey. The calculator subtracts the SNR from LC to give the protected level at the ear, then adds the HSE-recommended 4 dB real-world correction to account for the way protectors actually get worn in practice.
When to Use the SNR Method
The SNR method is the simplest of the three calculation methods but also the least precise. Use it when you’ve only got the protector’s SNR rating and a C-weighted workplace noise reading. If you have A-weighted and C-weighted readings, the HML method is more accurate. If you have octave-band data, the octave band method is more accurate still. The SNR method works well for relatively flat-spectrum noise but tends to over-estimate protection when noise is dominated by low frequencies (compressors, large fans), and under-estimate it when noise is mostly high frequency.
What the Result Tells You
You’re aiming for a level at the ear between 70 and 80 dB(A). The calculator returns an HSE protection rating in plain English. Below 70 dB(A) means the protector is over-protecting, which can make alarms and communication harder to hear. Above 85 dB(A) means it’s under-protecting. If your hearing protection programme isn’t getting workers into the target range, an independent noise consultant can carry out a proper survey and look at engineering controls at source.
This calculator uses the SNR method from BS EN ISO 4869-2 and HSE document L108. It’s intended as a guide.
About Advanced Noise Solutions
Advanced Noise Solutions is a specialist industrial noise consultancy based in St Albans. For 38 years we’ve helped UK manufacturers solve noise problems where they actually start, at the source, rather than wrapping the whole machine in an acoustic enclosure. Our AcoustiFix methodology typically delivers higher dB reductions than enclosures, at a fraction of the cost, with none of the access, visibility or maintenance trade-offs.
If your hearing protector isn’t bringing exposure into the 70 to 80 dB(A) target range, hearing protection alone isn’t the answer. We diagnose the real source of the noise and engineer a fix that brings unprotected exposure down. Get in touch or call us on 01727 864667 to talk it through.