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  2. Noise reduction coefficient - Wikipedia

    en.wikipedia.org/wiki/Noise_reduction_coefficient

    The noise reduction coefficient (commonly abbreviated NRC) is a single number value ranging from 0.0 to 1.0 that describes the average sound absorption performance of a material. An NRC of 0.0 indicates the object does not attenuate mid-frequency sounds, but rather reflects sound energy.

  3. Signal-to-noise ratio - Wikipedia

    en.wikipedia.org/wiki/Signal-to-noise_ratio

    If the noise has expected value of zero, as is common, the denominator is its variance, the square of its standard deviation σ N. The signal and the noise must be measured the same way, for example as voltages across the same impedance. Their root mean squares can alternatively be used according to:

  4. Sound transmission class - Wikipedia

    en.wikipedia.org/wiki/Sound_transmission_class

    It is based on the ASTM E-1332 Standard Classification for Rating Outdoor-Indoor Sound Attenuation. [37] Unlike the STC, which is based on a noise spectrum targeting speech sounds, OITC uses a source noise spectrum that considers frequencies down to 80 Hz (aircraft/rail/truck traffic) and is weighted more to lower frequencies. The OITC value is ...

  5. Friis formulas for noise - Wikipedia

    en.wikipedia.org/wiki/Friis_formulas_for_noise

    Friis's formula is used to calculate the total noise factor of a cascade of stages, each with its own noise factor and power gain (assuming that the impedances are matched at each stage). The total noise factor can then be used to calculate the total noise figure. The total noise factor is given as

  6. A-weighting - Wikipedia

    en.wikipedia.org/wiki/A-weighting

    A graph of the A-, B-, C- and D-weightings across the frequency range 10 Hz – 20 kHz Video illustrating A-weighting by analyzing a sine sweep (contains audio). A-weighting is a form of frequency weighting and the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. [1]

  7. Noise calculation - Wikipedia

    en.wikipedia.org/wiki/Noise_calculation

    Noise experts and some small specialized companies have slowly developed a limited number of calculation tools, which have increased in number and become more user-friendly, covering more application cases, and adding service elements to the noise calculation tools. The noise calculation process is complex in input (gathering data, correctly ...

  8. Noise curve - Wikipedia

    en.wikipedia.org/wiki/Noise_curve

    Noise can be an annoyance that creates fatigue and negatively affects productivity, safety and the ability to communicate. Therefore, standard methodologies for quantifying noise have been developed. Noise curves reflect different standardized means of creating a single number rating for the background noise spectrum in a space.

  9. SINAD - Wikipedia

    en.wikipedia.org/wiki/SINAD

    The ratio of (a) total received power, i.e., the signal to (b) the noise-plus-distortion power. This is modeled by the equation above. [2] The ratio of (a) the power of a test signal, i.e. a sine wave, to (b) the residual received power, i.e. noise-plus-distortion power. With this definition, it is possible to have a SINAD level less than one.