Structure and Classification of Grades
The sound level meter is composed of several parts, including a microphone, an attenuator (amplifier), a weight network, a root mean square detector, and an indicator head.
The measured sound pressure signal is converted into a voltage signal through a microphone, which is then passed through an attenuator, amplifier, and corresponding weighting network (or external filter), or input to an external recording instrument, or directly pushed by a root mean square detector to calibrate the indicator head in decibels.
The weighted network is a filtering circuit designed based on the equal response curve, divided into four types: A, B, C, and D.
The sound pressure level measured through a weighted network is called the weighted sound pressure level.
The sound pressure levels measured by the corresponding four weighted networks are called A sound level (LA), B sound level (LB), C sound level (LC), and D sound level (LD), respectively, denoted as dB (A), dB (B), dB (C), and dB (D).
Three types of weighted networks have varying degrees of attenuation against low-frequency noise, with A having the strongest attenuation, B taking the second place, and C having the weakest. Among them, the A-weighted network has the strongest attenuation to low-frequency noise and the most sensitive response to high-frequency noise, which is similar to the perception of noise by the human ear. Therefore, in the measurement of noise harmful to the human ear, A-weighted networks are used. The D-weighted network is specifically designed for aircraft noise measurement.
2、 Classification of Aihua sound level meters:
1. Sound level meters are divided into the following types based on their purpose:
General sound level meter
Pulse sound level meter
Integrating sound level meter
Noise exposure meter
2. According to its accuracy, it can be divided into the following categories:
Type 0 sound level meter (laboratory standard sound level meter)
Type 1 sound level meter (precision sound level meter for general purposes)
Type 2 sound level meter (general purpose sound level meter)
Type 3 sound level meter (conventional sound level meter).
