Multi-Objective NSGA-II Optimization for Broadband Beamforming with Spherical Harmonic Domain Assistance

Area of Science:

• Acoustics
• Signal Processing
• Array Signal Processing

Background:

• Sidelobe suppression is critical for wideband beamforming in acoustics.
• High noise and reverberation environments pose significant challenges.
• Existing methods struggle with optimal performance across various acoustic conditions.

Purpose of the Study:

• To propose a multi-objective NSGA-II wideband beamforming method for spherical microphone arrays.
• To enhance sidelobe suppression in challenging acoustic environments.
• To provide three-dimensional broadband beamforming capabilities.

Main Methods:

• Utilized a spherical harmonic domain for beamforming.
• Employed the NSGA-II optimization strategy with constraints.
• Optimized for white noise gain, directional index, and maximum sidelobe level.
• Estimated Pareto optimal solutions for broadband beamforming.

Main Results:

• Achieved superior sidelobe suppression across spherical harmonic orders compared to single-objective methods.
• Demonstrated effectiveness in a conference room setting.
• Obtained a white noise gain of 8.28 dB and max sidelobe level of -23.42 dB at low frequency.
• At high frequency, achieved comparable directivity index to Dolph-Chebyshev and SOCP, while outperforming them in white noise gain (16.14 dB) and max sidelobe level (-25.18 dB).

Conclusions:

• The proposed multi-objective NSGA-II method offers superior sidelobe suppression for wideband beamforming.
• The method is effective in real-world acoustic conditions, including noise and reverberation.
• This approach provides a robust solution for acoustic research requiring precise directional control.