Execution standard of noise tester
The HNT16040 sound level meter should be used to measure noise below 35 dB, and the measurement range should meet the needs of the measured noise, according to the GB12348-2008 and GB22337-2008 standards. This is because the first-class instrument performs much better than the second-class instrument. For instance, there may be a greater than 1.0dB difference in error between the accuracy level 2 instrument and the level 1 instrument.According to the new sound level meter standard, a level 1 sound level meter must operate between -10 and +50 degrees Celsius, and any change in sensitivity from the reference temperature within this range must not be larger than 0.5 decibels (dB). The meter's operating temperature range is 0°C to +40°C, and the difference in sensitivity within this temperature range in relation to the reference temperature is not greater than 1.0dB. It is obvious that level 1 instruments can better meet the requirements of environmental noise measurement since the majority of environmental noise monitoring instruments are used on site and the environmental conditions change significantly.
In the GB22337-2008 and GB12348-2008 standards, the indoor noise emission limit of structure-borne fixed equipment was proposed for the first time, stipulating that when the emitted noise is transmitted to the indoor noise-sensitive building through the building structure, the indoor equivalent sound level Neither the specified A sound level limit nor the specified indoor noise octave band sound pressure level limit (octave band center frequencies are 31.5Hz, 63Hz, 125Hz, 250Hz, 500Hz, and its coverage frequency is 22Hz-707Hz) It takes into account that whether it is the noise emitted by fixed equipment in industrial enterprises or the noise emitted by noise sources in social life, they are transmitted to the interior of noise-sensitive buildings through the building structure (referring to hospitals, school institutions, scientific research units, residences, etc. that need to be kept quiet) When the main component of the noise is low-frequency, the measured A sound level may not exceed the specified limit value, but the interference to people cannot be ignored, so only the A sound level limit cannot guarantee noise sensitivity For the indoor acoustic environment quality of buildings, the new standard adds the requirements for the limit value of the sound pressure level of the octave band in the low frequency band, and none of these limits should be exceeded. This requires the octave band spectrum analysis of the noise while measuring the A sound level .
There are many different types and performance levels of noise monitoring equipment. To measure the equivalent continuous sound level Leq, which is sufficient for environmental supervision departments, the instruments used for environmental noise monitoring should at least have the integration function of time averaging. However, environmental monitoring stations that need to measure traffic noise or conduct a noise census should also have 24-hour monitoring capabilities and statistical sound level LN (N=5, 10, 50, 90, 95) measurement capabilities.It is frequently essential to be equipped with microprinters, data transmission to computers, and data storage capabilities in order to reduce the amount of human recording and to facilitate subsequent data processing. Given that social life noise contains a lot of low-frequency components, it is challenging to assess how it will affect people using merely the A sound level. To determine whether the sound pressure level of each octave band is within the permitted range, the NR curve is used after measuring the A sound level and the octave spectrum analysis of the noise. For this, octave or 1/3 octave filtered noise spectrum analysis measurement devices are needed.
The measuring noise meter has a 24-hour real-time monitoring capacity with a decibel range of 30-130dB. The A/C weighting network is a widely used frequency weighting network.
