Reduction of nonlinear distortion in condenser microphones using a simple post-processing technique.

Area of Science:

• Acoustics
• Electrical Engineering
• Signal Processing

Background:

• Single-backplate condenser microphones, common in MEMS, studio recording, and lab measurements, suffer from nonlinear distortion.
• Reducing this distortion is crucial for high-fidelity audio capture and accurate measurements.

Purpose of the Study:

• To introduce a simple, effective post-processing technique for reducing nonlinear distortion in single-backplate condenser microphones.
• To demonstrate the technique's integration flexibility and performance across different microphone types and signal conditions.

Main Methods:

• Developed a post-processing algorithm based on a single, derivable parameter.
• Integrated the technique into external hardware (analog circuit, microcontroller, DSP) and on-chip for MEMS microphones.
• Validated the method using harmonic, two-tone, and multitone excitation on a MEMS microphone.

Main Results:

• Achieved approximately 40 dB reduction in second harmonic distortion under harmonic excitation.
• Demonstrated at least 20 dB reduction in second-order intermodulation products for complex signals.
• Confirmed that overestimating the parameter does not increase original distortion levels.

Conclusions:

• The proposed technique effectively reduces nonlinear distortion in condenser microphones across their operational range.
• Its simplicity and adaptability make it suitable for diverse audio applications, from consumer electronics to professional equipment.
• This method offers a practical solution for improving the linearity and fidelity of microphone systems.