Comparison of multimicrophone probe design and processing methods in measuring acoustic intensity

Area of Science:

• Acoustics
• Signal Processing

Background:

• Accurate acoustic intensity measurement is crucial for noise source identification and sound field analysis.
• Multimicrophone probes offer potential for improved acoustic intensity estimation.
• Understanding inherent biases in different probe designs and processing methods is essential.

Purpose of the Study:

• To numerically analyze the bias in acoustic intensity measurements for various multimicrophone probe configurations.
• To compare the performance of four-microphone (regular tetrahedral, orthogonal) and six-microphone probes.
• To investigate the influence of microphone embedding and processing methods on measurement accuracy.

Main Methods:

• Numerical analysis of acoustic intensity bias for plane wave fields.
• Consideration of probes with microphones embedded and not embedded on a rigid sphere.
• Evaluation of finite-sum and finite-difference processing methods for pressure and particle velocity estimation.

Main Results:

• The orthogonal probe, using the origin microphone for pressure, exhibited the lowest intensity magnitude bias.
• The six-microphone probe, averaging 15 intensity components, demonstrated the lowest intensity direction bias.
• Bias was analyzed in terms of root-mean-square average and maximum bias as a function of the angle of incidence.

Conclusions:

• Specific multimicrophone probe designs and processing methods can minimize acoustic intensity bias.
• Correction factors derived from numerical analysis can enhance probe performance.
• The choice of dimensionless frequency definition impacts the analysis results.