Enhancing the coherence between virtual and physical signals in virtual sensing with a double-layer microphone...

Area of Science:

• Acoustics
• Signal Processing
• Control Systems

Background:

• Signal coherence is crucial for active noise control (ANC) performance using virtual sensing.
• Existing single-layer microphone arrangements have limitations in achieving optimal coherence.

Purpose of the Study:

• To propose and evaluate a double-layer physical microphone arrangement for enhanced coherence in virtual sensing ANC.
• To improve the upper limit frequency of noise reduction performance.

Main Methods:

• Distributing physical microphones on two concentric hemispherical surfaces around a virtual microphone.
• Comparing the double-layer arrangement with a single-layer setup using simulations in diffuse fields and experiments in reverberation rooms.
• Analyzing sound pressure gradient information from the dual layers.

Main Results:

• The double-layer arrangement significantly outperforms the single-layer arrangement in maintaining high coherence (>0.9).
• The upper limit frequency for effective noise reduction is demonstrably increased with the proposed method.
• Further improvements were observed by optimizing the distance between layers and radial microphone alignment.

Conclusions:

• The proposed double-layer physical microphone configuration effectively enhances signal coherence for virtual sensing ANC.
• This approach offers a practical solution for improving noise reduction performance in challenging acoustic environments.
• The findings are validated through simulations and experiments, including real-world vehicle noise conditions.