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Perceived Noise Reduction
The following table shows various dB levels and the corresponding reduction in actual sound pressure level (SPL) as well as the human perceived volume reduction for reducing noise levels.
| dB | Actual SPL Reduction | Perceived Volume Reduction |
| 3 dB | 50.00% | 18.77% |
| 6 dB | 75.00% | 34.02% |
| 9 dB | 87.50% | 46.41% |
| 12 dB | 93.75% | 56.47% |
| 15 dB | 96.88% | 64.64% |
| 18 dB | 98.44% | 71.28% |
| 21 dB | 99.22% | 76.67% |
| 24 dB | 99.61% | 81.05% |
| 27 dB | 99.80% | 84.61% |
| 30 dB | 99.90% | 87.50% |
| 33 dB | 99.95% | 89.85% |
| 36 dB | 99.98% | 91.75% |
| 39 dB | 99.99% | 93.30% |
| 42 dB | 99.99% | 94.56% |
| 45 dB | 100.00% | 95.58% |
| 48 dB | 100.00% | 96.41% |
| 51 dB | 100.00% | 97.08% |
| 54 dB | 100.00% | 97.63% |
| 57 dB | 100.00% | 98.08% |
| 60 dB | 100.00% | 98.44% |
| 63 dB | 100.00% | 98.73% |
| 66 dB | 100.00% | 98.97% |
| 69 dB | 100.00% | 99.16% |
| 72 dB | 100.00% | 99.32% |
| 75 dB | 100.00% | 99.45% |
| 78 dB | 100.00% | 99.55% |
| 81 dB | 100.00% | 99.64% |
