Electret condenser microphone achieves high fidelity reproduction of human voice details through the following technical features: sensitive acoustic electric conversion mechanism, microscopic vibration analysis ability? Low distortion amplification system, directional optimization design, transient response control.
Sensitive acoustic electric conversion mechanism
The surface of the polarizer diaphragm has permanent charges, and acoustic vibration causes a change in the distance between the diaphragm and the back plate, resulting in a change in capacitance and directly outputting high linearity electrical signals.
This passive conversion mode avoids the external polarization voltage interference of traditional capacitor microphones, and the electret microphone can capture sound waves in the full frequency range of 20Hz-20kHz, fully covering the human voice fundamental frequency (85-255Hz) and overtone components.
Microscopic vibration analysis ability
The electret microphone head adopts a 6-10 μ m ultra-thin polymer electret film, with a mass of only 0.2-0.5mg and a displacement sensitivity of 0.001mm level.
It can accurately pick up subtle harmonics generated by vocal cord vibration (tooth sound 4-8kHz, lip sound 2-4kHz), with a signal-to-noise ratio of over 68dB and equivalent noise ≤ 18dBA.
Low distortion amplification system
The integrated JFET impedance converter (input impedance ≥ 1G Ω) amplifies the pA level current signal, paired with a low-noise operational amplifier (noise figure<3dB), resulting in total harmonic distortion<0.5%.
Ensure that the sound pressure level of the polarizer microphone maintains a linear response within the dynamic range from 40dB SPL to 134dB SPL.
Directional optimization design
The heart-shaped directional structure of the polarizer microphone reduces environmental noise in the 140 ° direction by 15-20dB and increases axial sensitivity by 4-6dB through the principle of phase cancellation, effectively enhancing speech clarity.
The acoustic design of the electret microphone head cavity ensures frequency response fluctuations of less than ± 2dB, ensuring sound reproduction.
Transient response control
The resonant frequency of the polarizing microphone diaphragm is designed to be above 30kHz, with a group delay of less than 10 μ s. It can accurately capture 5ms level transient waveforms of speech plosives (such as/p/,/t/), with a rise time of ≤ 20 μ s, avoiding sound tail distortion.
Electret microphone technology is widely used in conference systems, speech recognition, medical auscultation, and other fields.
Under typical parameters of signal-to-noise ratio of 70dB and sensitivity of -36dBV/Pa, the microphone can achieve a speech feature retention rate of over 94%, meeting the PSQM speech quality assessment requirements of ITU-T P.861 standard.