What is a sound level meter (or noise meter)?
Name Explanation:
There are generally three types of weighting networks: A, B, and C. A-weighted sound level simulates the frequency characteristics of low intensity noise below 55dB in the human ear, B-weighted sound level simulates the frequency characteristics of medium intensity noise from 55dB to 85dB, and C-weighted sound level simulates the frequency characteristics of high-intensity noise. The main difference among the three is the degree of attenuation of the low-frequency components of noise, with A attenuating more, B taking second place, and C * decreasing. A-weighted sound level is widely used in noise measurement worldwide due to its characteristic curve approaching the auditory characteristics of the human ear, while B and C are gradually no longer used.
Definition:
A noise meter, also known as a sound level meter, is a fundamental instrument in noise measurement. A sound level meter generally consists of a capacitive microphone, preamplifier, attenuator, amplifier, frequency meter network, and effective value indicator head. The working principle of a sound level meter is that the sound is converted into an electrical signal by a microphone, and then the impedance is changed by a preamplifier to match the microphone with the attenuator. The amplifier adds the output signal to the network, performs frequency weighting (or external filtering) on the signal, and then amplifies the signal to a certain amplitude through attenuators and amplifiers, and sends it to the effective value detector.
Classification:
1. From the perspective of the measurement object, it can be divided into the measurement of environmental noise (sound field) characteristics and the measurement of sound source characteristics.
2. From the time characteristics of the sound source or sound field, it can be divided into steady-state noise measurement and non-stationary noise measurement. Non steady state noise can be further divided into periodic variation noise, irregular variation noise, and pulse sound.
3. From the frequency characteristics of the sound source or field, it can be divided into broadband noise, narrowband noise, and noise containing prominent pure tone components.
4. From the perspective of measurement accuracy requirements, it can be divided into precision measurement, engineering measurement, and noise survey.
