Appendix: Total Noise Suppression Ratio - Sony MDR-NC300D Manual De Instrucciones

Appendix: Total Noise Suppression Ratio
Previously, only the sound pressure loss at a specific frequency was indicated as the canceling performance. However, Sony has
proposed a unit showing the loss of sound "energy" as a closer expression of the listener's impression.
The total noise suppression ratio (TNSR) of noise canceling headphones is expressed by the following formula.
TNSR = 10 log (P/P
P = Energy of sound observed at the ear when not wearing headphones
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P = Energy of sound observed at the ear when wearing headphones
* The above energy of sound measurements are weighted.
TNSR is the value measured using the noise signal based on a broad spectrum.
As compared with the method of measuring the noise canceling ratio at one frequency, TNSR enables the canceling performance
in the actual usage environment to be more objectively evaluated.
Moreover, the canceling performance in each noise environment can be evaluated using the signals to simulate the spectrum
distribution of real-world noise such as a plane or train.
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