Factors to consider when choosing a sound level meter
A sound level meter is an instrument that measures the sound pressure level and sound level according to a certain frequency weighting and time weighting. It is the most commonly used instrument in acoustic measurement. It can measure the noise level of industrial noise, traffic noise, environmental noise and living noise, etc. according to the auditory characteristics of human ears.
Sound level meters can be used in the measurement of environmental noise, mechanical and electrical product noise, traffic noise, architectural acoustics, and electroacoustics. Some sound level meters can also be used to measure vibration by replacing the receiving part. The sound level meter is externally connected or internally set an octave filter or a 1/3 octave filter, which can perform noise spectrum analysis.
With the development of electronic technology, especially large-scale integrated circuits and computer technology, frequency weighting, detectors and filter circuits in sound level meters are all realized by digital signal processing technology instead of analog circuits. This not only makes the circuit more simplified, the dynamic range is wider, but also the function and stability are greatly improved, especially real-time spectrum analysis can be realized, which makes the sound level meter more widely used.
The sound level meter is composed of microphones, attenuators, weighting networks, amplifiers, detection networks and indicators. The most advanced part of the sound level meter is the microphone, which converts the sound energy into electrical energy and sends it to the preamplifier of the host, after amplification, it is sent to the attenuator and the weighting network, and finally passes through the wave detection and is indicated by a certain damping characteristic. The meter shows the sound level reading.
Factors to consider when choosing a sound level meter:
Price: When purchasing a sound level meter, you first need to consider the price range of the product. The price of a sound level meter depends on many factors, including features, accuracy class, number of channels, storage capacity, and more. Generally speaking, domestic sound level meters with the same indicators are much cheaper than imported products.
Function: For the sound level meter, the measurement function is the most important index, which not only determines the application range of the sound level meter, but also has the greatest relationship with the price of the sound level meter. According to the type of the signal to be measured, for steady-state noise signals, the function of the sound level meter is only to measure the instantaneous sound pressure level; for the measurement of unsteady-state signals, it is generally required to measure the time-average sound level or the equivalent sound level; For spectrum analysis, a noise spectrum analyzer should be selected.
Number of channels: A general sound level meter has only one channel, and only one channel of sound pressure level is measured. Sometimes it is necessary to measure multi-channel sound pressure levels, so it is necessary to use multiple channels. For example, two channels are required to measure sound intensity levels, and more channels are required to measure sound power levels. Multi-channel sound level meters greatly expand the use of sound level meters.
Accuracy class: Accuracy class of sound level meter: Class 1 and Class 2.
Spectrum analysis function: In order to perform spectrum analysis on noise, it is necessary to select the spectrum analysis function. Octave and 1/3 octave spectrum analysis are the most widely used in acoustic measurements. In the past, spectrum analysis was realized using analog filters, but now most of them use digital technology, and real-time spectrum analysis is carried out through digital filters.
Measuring range: The measuring range of the sound level meter sometimes needs to consider its measurement upper limit in order to measure high sound pressure levels, such as 140dB, or even above 160dB; sometimes it needs to consider its measurement lower limit in order to measure low sound pressure levels, such as below 20dB ; Usually the measurement range of the sound level meter is in the range of 25dB to 130dB.
Interface: The current sound level meter generally has RS232, USB and other interfaces, which are used to connect to a micro-printer or computer, and users can choose according to the test needs.
Calibration: The sound level meter needs to use a sound calibrator for sound calibration during use. The sound calibrator is often used as a supporting instrument for the sound level meter and becomes an integral part of the sound level meter. There are two types of sound calibrator: piston sounder and sound level calibrator. The piston sounder produces 250Hz, 124dB sound pressure level, and the accuracy level is 1 or 0; the sound level calibrator produces 1000Hz, 94dB sound pressure level, and the accuracy is The grade is either level 2 or level 1. A level 1 sound level meter needs to be calibrated with a level 1 or level 0 sound calibrator, and a level 2 sound level meter needs to be calibrated with a level 2 or level 1 sound calibrator.
