What is the difference between the noise meter professional version and the non-professional version?
The noise meter is the most basic noise measuring instrument. It is an electronic instrument, but it is different from objective electronic instruments such as voltmeters.
When converting an acoustic signal into an electrical signal, it can simulate the time characteristics of the human ear's response speed to sound waves; there are characteristics of different sensitivities and intensity characteristics of changing characteristics at different loudnesses.
It can also be said that the noise meter is an electronic instrument with subjectivity.
The working principle of the noise meter is that the microphone converts the sound into an electrical signal, and then the preamplifier transforms the impedance to match the microphone with the attenuator. The amplifier adds the output signal to the weighting network, performs frequency weighting on the signal (or an external filter), and then amplifies the signal to a certain amplitude through the attenuator and the amplifier, and sends it to an effective plant detector (or an external press circuit) Level recorder), the value of the noise level is given on the indicator head. The sound pressure level measured by the noise meter/sound level meter through the frequency weighting network is called the sound level. According to the weighting network used, it is called A sound level, B sound level and C sound level. Network, the units are denoted as dB(A), dB(B) and dB(C). The A network is to simulate the human ear's response to the 40-square pure tone in the equal-loudness curve. Its curve shape is opposite to the 340-square equal-loudness curve, so that the middle and low frequency bands of the electrical signal have a greater attenuation. The B network simulates the human ear's response to the 70-square pure tone, and it attenuates the low-frequency band of the electrical signal to a certain extent. The C network simulates the response of the human ear to a 100-square pure tone, and has a nearly flat response throughout the entire audio frequency range. The digital noise meter measured by Yuwen uses two frequency weightings, A and C: A weighting attenuates the low-frequency components of the original environmental noise signal more, simulating the auditory characteristics of the human ear, and evaluating the noise from the auditory perspective Therefore, it is the most widely used; C-weighting has less modification to the original noise signal of the environment, and can truly reflect the noise level of the environment.
The difference between the professional version and the non-professional version
Their core difference lies in 2 aspects: acoustic sensor and circuit board.
(1) The acoustic sensor is the core component. The cheap MEMS is definitely used, and it is used for mobile phone calls. It has poor stability and narrow frequency response range. There are thousands of good acoustic sensors. So a few hundred yuan is the cheapest sound level meter.
(2) Circuit board differences, in order to measure accurately, the instrument must meet EMC. Professional sound level meters should obtain type approval certificates (mandatory requirements of the metrology law, provincial or above metrology institutions can do it) before they can be produced and sold. In order to pass the model batch, sensors, circuit boards, casings, etc. have to be processed, and these costs may add up to more than 1,000 yuan.
(3) If it is just for fun, just buy a sound level meter, otherwise buy a professional one. You don't always want the same sound, today you measure 50 dB, tomorrow it might be 52 dB, and the temperature changes the day after tomorrow, and it becomes 47 dB again....
(4) The data measured by non-standard sound level meters is generally low, and it is easy to pass the test during acceptance....
