Noise meter, also known as sound level meter, is an instrument used to measure the sound pressure level or sound level of sound. It is a basic and commonly used instrument in acoustic measurement. With the development of the national economy and the improvement of people's material and cultural living standards , noise census and environmental protection work have been carried out in an all-round way. The machinery manufacturing industry has taken noise as one of the important quality indicators of products. Buildings such as auditoriums and gymnasiums not only require beautiful appearance, but also pursue sound effects, which makes the application of noise meters more and more. more and more widely.
Now it is not only used in acoustic and electroacoustic measurement, but also has been widely used in machine manufacturing, architectural design, transportation, environmental protection, medical and health and national defense engineering and other fields, becoming an acoustic measurement instrument that almost all departments must have .
Whether the noise meter is used correctly or not directly affects the accuracy of the measurement results. Therefore, it is necessary to introduce the use of noise meters.
1. Selection of the environment where the noise meter is used: Select a representative test site. The noise meter should be left off the ground and the wall to reduce the additional impact of the reflected sound from the ground and wall.
2. Weather conditions require that when there is no rain or snow, the noise meter should keep the microphone diaphragm clean, and the wind hood must be added when the wind is above level 3 (to avoid wind noise interference), and the measurement should be stopped for strong winds above level 5.
3. Open the carrying case of the noise meter, take out the noise meter, and put on the sensor.
4. Put the noise meter in A state, check the battery, and then calibrate the noise meter.
5. The comparison table (generally common ambient sound level reference), adjust the measurement range.
6. You can use fast (measure the instantaneous value of the environment where the sound pressure level changes greatly), slow (measure the average value in the environment where the sound pressure level changes little), pulse (measure the pulse sound source), filter ( The sound level of the measurement band) is measured with various functions.
7. Record data as needed, and can also connect to a printer or other computer terminals for automatic collection. Organize equipment and put it back in place
How to use the noise meter
1. Check the calibration of the noise meter with a sound calibrator
2. Set the range switch to the appropriate gear according to the size of the measured sound. If the size cannot be estimated, set it to "85-130"
3. Put the time weighting switch at the position specified by the standard; when the sound level is relatively stable, set it to "F" (fast); when the sound level changes drastically, set it to "S" (slow)
4. Set the reading mark switch to "5S" or "3S"
5. Set the power switch to "On"; the instrument displays numbers when it starts to work
6. If the right end of the display shows the excess mark "▲" (the under-volume mark "▼"), the range switch should be moved up or down to make the range mark disappear. If the range mark cannot disappear, the measured sound level at the time of the meter exceeds the measuring range of the instrument.
7. After adjusting the range of the noise meter, you can read the measurement results from the display.
8. Make measurement records
9. After the measurement, it is recommended to check the sensitivity of the noise meter with an acoustic calibrator to ensure the accuracy and reliability of the measurement data.
10. Set the power switch to "Off". If the instrument will not be used for a long time, be sure to remove the battery.
Second, the use of noise meter precautions
1. When measuring, the instrument should choose the correct gear according to the situation, hold the noise meter with both hands flat on both sides, and point the microphone to the sound source to be measured. Extension cables and extension rods can also be used to reduce the influence of the noise meter’s appearance and human body on the measurement. . The location of the noise meter should be determined according to relevant regulations.
2. The noise meter is powered by a battery, and it should be checked whether the battery voltage meets the requirements: the meter function switch is set to the "battery" gear, and the "attenuator" can be set arbitrarily. At this time, the indication on the meter should be within the rated battery voltage range, otherwise it needs to Replacement battery. When installing the battery or external power supply, pay attention to the polarity, and do not reverse the connection. If the battery is not used for a long time, the battery should be removed to avoid leakage and damage to the instrument.
3. Read the manual before use to understand the use method and precautions of the instrument. Preheat according to the preheating time (for example, 10 minutes) specified in the operation manual of the noise meter
4. The battery voltage used by the noise meter should be replaced when the voltage is insufficient.
5. Calibrate the amplifier gain: the meter function switch is set to "0", and the "attenuator" switch is set to "calibration". At this time, the meter pointer should be at the red line position, otherwise the sensitivity potentiometer needs to be adjusted.
6. When you don't know how big the measured sound level is, you must put the "attenuator" at the large attenuation position (for example, 120dB), and then gradually adjust it to the attenuation position required by the measured sound level during measurement to prevent the measured sound level. The sound level exceeds the range and destroys the noise meter
7. Do not disassemble the microphone to prevent throwing, and place it properly when not in use.
8. The sensor is a relatively expensive component that is extremely delicate and easily damaged, so be careful to handle it during the whole experiment. After the experiment, remove the place where the sensor was placed.
9. The instrument should not be placed in places with high temperature, humidity, sewage, dust and air or chemical gas with high hydrochloric acid and alkali components.
10. Do not disassemble the instrument without authorization. If the instrument is not normal, it can be sent to the repair unit or the factory for overhaul.
3. Sensitivity calibration
A. In order to ensure the accuracy of the measurement, the noise meter should be carefully calibrated before and after each measurement.
B. Match the sound level calibrator to the microphone, turn on the calibration power supply, read the value, adjust the sensitivity potentiometer of the noise meter, and complete the calibration.
Fourth, the type of noise meter
Noise meter is an instrument that measures the sound pressure level and sound level of sound according to certain frequency weighting and time weighting. It is a basic instrument commonly used in acoustic measurement. The noise meter can be used for the measurement of environmental noise, machine noise, vehicle noise and other various noises, as well as for the measurement of electroacoustics, architectural acoustics, etc.
In order to make the measurement results of noise meters produced in various countries in the world can be compared with each other, the International Electrotechnical Commission (IEC) has formulated relevant standards for noise meters and recommended that countries adopt them. my country's national standard for sound level meters is GB3785-83 "Noise Meter Electrical and Acoustic Performance and Test Methods". In 1984, IEC passed the IEC804 "Integral Average Noise Meter" international standard, and in 1997 my country promulgated GB/T17181-1997 "Integral Average Noise Meter". They are consistent with the main requirements of the IEC standard. In 2002, the International Electrotechnical Commission (IEC) issued a new international standard IEC61672-2002 "Noise Meter". This standard replaces the original IEC651-1979 "Noise Meter" and IEC804-1983 "Integrated Average Noise Meter". According to this standard, my country has formulated the JJG188-2002 "Noise Meter" verification regulations. Compared with the old standards, the new international standards and national verification regulations for noise meters have been greatly revised.
