What is the meaning of the weighted weighting of the noise meter?
It is the ratio of the useful signal power to the useless noise power. Normally, since power is a function of current and voltage, the signal-to-noise ratio can also be calculated using the voltage value, i.e. the ratio of the signal level to the noise level, but with a slightly different formula. Calculation of S/N ratio by power: S/N=10 log Calculation of S/N ratio by voltage: S/N=10 log Since the S/N ratio is logarithmically related to the power or the voltage, the ratio of the output value to the noise level has to be increased significantly if the S/N ratio is to be improved.
In many product manuals in the specification table behind the data, there will often be a word A, meaning A-weight, that is, A weighting, weighting means that a certain value according to certain rules weighing the importance of the modifications, due to the human ear on the mid-frequency is particularly sensitive, so if an amplifier in the mid-frequency band signal-to-noise ratio is large enough then, even if the signal-to-noise ratio in the low-frequency and high-frequency bands slightly lower than that the human ear is not easy to detect. If the signal-to-noise ratio is measured with weighting, the value will be higher than without weighting. In the case of A-weighting, the value will be higher than without weighting.
In addition: in order to simulate the human ear hearing in different frequencies have different sensitivity, in the sound level meter is equipped with a can simulate the hearing characteristics of the human ear, the electrical signal corrected to the auditory approximation of the value of the network, this network is called the weighting network. The sound pressure level measured by the weighting network is no longer the objective physical sound pressure level (called linear sound pressure level), but the sound pressure level corrected by the sense of hearing, called the weighted sound level or noise level.
The weighting network generally has A, B, C. A weighted sound level is the simulation of the human ear on the frequency characteristics of low-intensity noise below 55dB, B weighted sound level is the simulation of the frequency characteristics of medium-intensity noise from 55dB to 85dB, and C weighted sound level is the simulation of the frequency characteristics of high-intensity noise. The main difference between the three is the degree of attenuation of the low-frequency components of the noise, A attenuation * more, followed by B, C * less. A-weighted sound level due to its characteristic curve is close to the auditory properties of the human ear, so it is currently the world's noise measurements in the application of the * widely used one of the B, C has been gradually not used.
The noise level reading from the sound level meter must indicate the measurement conditions, such as the unit of dB, and the use of the A-weighting network, it should be recorded as dB (A).
