What is the meaning of the weighted weighting of a sound level meter?
It refers to the ratio of useful signal power to useless noise power. Usually, because power is a function of current and voltage, the signal-to-noise ratio can also be calculated using voltage, which is the ratio of signal level to noise level. However, the calculation formula is slightly different. Calculating signal-to-noise ratio based on power ratio: S/N=10 log Calculating signal-to-noise ratio based on voltage: S/N=10 log Due to the logarithmic relationship between signal-to-noise ratio and power or voltage, to increase the signal-to-noise ratio, it is necessary to significantly increase the ratio of output value to noise value. For example, when the signal-to-noise ratio is 100dB, the output voltage is 10000 times the noise voltage. For electronic circuits, this is not an easy task. Humidity sensor probe, stainless steel electric heating tube PT100 sensor, cast aluminum heater, heating coil fluid solenoid valve
If an amplifier has a high signal-to-noise ratio, it means a quiet background. Due to the low noise level, many weak sound details masked by noise will be revealed, causing an increase in floating sound, a stronger sense of air, and an increased dynamic range. There is no strict discrimination data to determine whether the signal-to-noise ratio of an amplifier is good or bad. Generally speaking, a value of about 85dB or higher is better. If it is lower than this value, it is possible to hear obvious noise in music gaps during certain loud listening situations. In addition to signal-to-noise ratio, the concept of noise level can also be used to measure the noise level of an amplifier. This is actually a signal-to-noise ratio value calculated using voltage, but the denominator is a fixed number: 0.775V, and the numerator is the noise voltage. Therefore, the noise level and signal-to-noise ratio are: the former is an absolute number, and the latter is a relative number.
After the specification sheet data in many product manuals, there is often an A word, meaning A-weight, which means that a certain value has been modified according to certain rules. Since the human ear is particularly sensitive to the intermediate frequency, if the signal-to-noise ratio in the intermediate frequency band of an amplifier is large enough, even if the signal-to-noise ratio is slightly lower in the low and high frequency bands, it is not easy for the human ear to detect. It can be seen that if the weighting method is used to measure the signal-to-noise ratio, its value will definitely be higher than if the weighting method is not used. In terms of A weighting, its value will be higher than without weighting.
In addition, in order to simulate the different sensitivities of human auditory perception at different frequencies, a network is installed in the sound level meter that can simulate the auditory characteristics of the human ear and correct the electrical signal to an approximate value of the auditory sensation. This network is called a weighted network. The sound pressure level measured through a weighted network is no longer an objective physical quantity sound pressure level (called linear sound pressure level), but a sound pressure level corrected by auditory perception, called weighted sound level or noise level.
There are generally three types of weighting networks: A, B, and C. A-weighted sound level simulates the frequency characteristics of low intensity noise below 55dB in the human ear, B-weighted sound level simulates the frequency characteristics of medium intensity noise from 55dB to 85dB, and C-weighted sound level simulates the frequency characteristics of high-intensity noise. The main difference among the three is the degree of attenuation of the low-frequency components of noise, with A having the most attenuation, followed by B, and C having the least. A-weighted sound level is currently the most widely used type of noise measurement in the world due to its characteristic curve close to the auditory characteristics of the human ear, while B and C are gradually no longer used.
The noise level reading obtained from the sound level meter must indicate the measurement conditions. If the unit is dB and an A-weighted network is used, it should be recorded as dB (A).
