Adaptive phase calibration of a microphone array for acoustic holography

Area of Science:

• Acoustics
• Signal Processing
• Array Signal Processing

Background:

• Low-frequency sound field recording with circular microphone arrays is limited by microphone phase mismatch.
• Phase variations are more significant at low frequencies due to lower amplitude high-order phase modes.

Purpose of the Study:

• To demonstrate the feasibility of a self-calibration method for improving low-frequency holographic sound field recording.
• To correct phase mismatches in microphone arrays at low frequencies using source location information.

Main Methods:

• Estimating wide-band source locations using mid-range frequencies.
• Using source location data to correct microphone array phase at low frequencies.
• Initial calibration in an anechoic environment, followed by adaptive calibration for reverberant conditions.

Main Results:

• Demonstrated feasibility of self-calibration in an anechoic environment using high-quality microphones.
• Extended the technique to adaptive calibration effective in mildly reverberant environments.
• Validated the adaptive approach using inexpensive microphones.

Conclusions:

• The self-calibration method effectively corrects low-frequency phase mismatches in microphone arrays.
• Adaptive calibration enables accurate holographic sound field recording in less ideal acoustic environments.
• The technique holds promise for improving audio recording quality with various microphone arrays.