The principles and applications of sound level meters
The microphone converts the sound into an electrical signal, and then the preamplifier changes the impedance to match the microphone and the attenuator. The amplifier adds the output signal to the weighting network, performs frequency weighting on the signal (or external filter), and then amplifies the signal to a certain amplitude through the attenuator and amplifier, and sends it to the effective value detector (or external voltage detector). Level recorder), giving the value of the noise level on the indicator head.
application
The sound level meter is a basic instrument for measuring noise. It is an electronic instrument. The sound level meter generally consists of a condenser microphone, a preamplifier, an attenuator, an amplifier, a frequency weighting network, and an effective value indicator meter. Sound level meters can be divided into two categories according to their sensitivity, one is ordinary sound level meters; the other is precision sound level meters. According to the use of sound level meters, they can also be divided into two categories: one is used to measure stability. State noise; one type is used to measure unstable noise and impulse noise.
The sound level meter adopts advanced digital detection technology, which greatly improves the stability and reliability of the instrument. The sound level meter has the advantages of simple operation and convenient use; it has the characteristics of large dynamic range, large-screen LCD digital display, automatic measurement and storage of various data, etc.
Sound level meters can be widely used in industrial noise measurement and environmental noise measurement of various machines, vehicles, ships, electrical appliances, etc., and are suitable for factories and enterprises, architectural design, environmental protection, labor health, transportation, teaching, medical and health, scientific research and other departments. The field of acoustic testing.
Generally, two-stage amplifiers are used, namely input amplifier and output amplifier, whose function is to amplify weak electrical signals. The input attenuator and output attenuator are used to change the attenuation of the input signal and the attenuation of the output signal so that the meter pointer points at the appropriate position. The attenuator adjustment range used by the input amplifier is the measurement low end, and the attenuator adjustment range used by the output amplifier is the measurement range. Many sound level meters have a cutoff of 70dB for the high and low ends.
