Comparison of multi-microphone probes and estimation methods for pressure-based acoustic intensity

Rose, Michael T.; Rasband, Reese D.; Gee, Kent L.; Sommerfeldt, Scott D.

doi:10.1121/2.0000787

Cited by 1 publication

(2 citation statements)

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“…Below f lim , the errors are extremely small, with one noted exception; for h n ¼ 0 the non-trivial error above around 15 kHz is caused by probe scattering. 32 The level bias is especially noticeable, because scattering off the front microphone shields the center microphone, the auto-spectrum of which is used to give the analytical intensity level. For this reason, other small, non-zero angular separation angles do not exhibit these increased bias errors.…”

Section: B Experimental Resultsmentioning

confidence: 99%

“…To reduce scattering, a greater microphone separation distance is beneficial. 32 Probe rotation such that microphones no longer shield one another is also a viable option. Increasing the microphone separation also decreases the spatial Nyquist frequency, which reduces the usable bandwidth when using the traditional method for calculating intensity; for the PAGE method, a greater microphone separation distance decreases f lim , though as the angular separation between the signal and additive noise source goes to zero, f lim becomes infinite.…”

Section: Discussionmentioning

confidence: 99%

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Bandwidth extension of narrowband-signal intensity calculation using additive, low-level broadband noise

Cook

Succo

Gee

et al. 2019

The Journal of the Acoustical Society of America

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Calculation of acoustic intensity using the phase and amplitude gradient estimator (PAGE) method has been shown to increase the effective upper frequency limit beyond the traditional p-p method when the source of interest is broadband in frequency [Torrie, Whiting, Gee, Neilsen, and Sommerfeldt, Proc. Mtgs. Acoust. 23, 030005 (2015)]. PAGE processing calculates intensity for narrowband sources without bias error up to the spatial Nyquist frequency [Succo, Sommerfeldt, Gee, and Neilsen, Proc. Mtgs. Acoust. 30, 030015 (2018)]. The present work demonstrates that for narrowband sources with frequency content above the spatial Nyquist frequency, additive low-level broadband noise can improve intensity calculations. To be effective, the angular separation between the source and additive noise source should be less than 30 , while using phase unwrapping with a smaller angular separation will increase the usable bandwidth. The upper frequency limit for the bandwidth extension depends on angular separation, sound speed, and probe microphone spacing. Assuming the signal-to-additive-noise ratio (SNR a) is larger than 10 dB, the maximum level and angular bias errors incurred by the additive broadband noise beneath the frequency limit-or up until probe scattering effects must be taken into account-are less than 0.5 dB and 2:5 , respectively. Smaller angular separation yields smaller bias errors. V

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Section: B Experimental Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%