Panel acoustic contributions examination

• US 20070189550A1
• Filed: 02/14/2006
• Published: 08/16/2007
• Est. Priority Date: 02/14/2006
• Status: Abandoned Application

• Current Assignee: Wayne State University
• Original Assignee: Wayne State University
• Inventors: Wu, Sean
• Application Number:
  US11/354,214
• Publication Number:
  US 20070189550A1
• Time in Patent Office: Days
• US Class Current: 381/94.100
• CPC Class Codes: G01H 3/125 for representing acoustic field distribution using optical means G01H9/002; sonar systems for imaging G01S7/56, G01S15/89; acoustic holography G03H3/00
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 3/02 for preventing acoustic reaction , i.e. acoustic oscillatory feedback specially adapted for hearing aids H04R25/453

Abstract

A system for analyzing noise sources correlates the sound pressure level value at any field point to the acoustic energy directly flowing out of any individual panel of a vibrating structure. This acoustic energy flow or acoustic intensity depicts how sound radiates and in which direction a sound wave propagates in the field. Therefore, the result represents a true contribution of an individual panel to an acoustic field. The acoustic intensity on the surface of a vibrating object is reconstructed by the Helmholtz equation least squares (HELS) based nearfield acoustical holography (NAH). The acoustic intensity is utilized to establish correlations between user-designated panels and the SPL value at any field point. With this information users can rank the order of contributions from individual panels of any vibrating structure to an acoustic field. These order ranking and panel contribution analyses help engineers to come up the best strategy to tackle various noise issues in the most cost-effective manner. The method is applicable to both interior and exterior regions.

Claims

1. A method for analyzing noise including the steps of:

measuring acoustic pressure at a plurality of locations near a noise source;

reconstructing a surface acoustic pressure and a normal surface velocity on a source surface of the noise source based upon the measured acoustic pressures at the plurality of locations;

reconstructing a normal component of acoustic intensity on the source;

creating a pressure-to-pressure transfer function that correlates the surface acoustic pressure to field acoustic pressure; and

creating a pressure-to-velocity transfer function that correlates the normal surface velocity to the field acoustic pressure.

2. The method of claim 1 further including the step of dividing the pressure-to-pressure transfer function and the pressure-to-velocity transfer function into individual components that cover a plurality of panel surfaces of the noise source.

3. The method of claim 2 further including the step of comparing amplitudes and phases of contributions from each of the plurality of panel surfaces to noise at a designated point.

4. The method of claim 3 further including the step of ranking the contributions from each of the plurality of panel surfaces.

5. A system for diagnosing noise comprising:

a plurality of microphones for measuring acoustic pressure at a plurality of locations;

a processor receiving signals from the plurality of microphones indicative of the acoustic pressure at the plurality of locations, the processor programmed to reconstruct a surface acoustic pressure and a normal surface velocity on a source surface of the noise source based upon the measured acoustic pressures at the plurality of locations, the processor programmed to reconstruct a normal component of acoustic intensity on the source, the processor programmed to create a pressure-to-pressure transfer function that correlates the surface acoustic pressure to field acoustic pressure, the processor programmed to create a pressure-to-velocity transfer function that correlates the normal surface velocity to the field acoustic pressure.

6. A method for analyzing noise including the steps of:

measuring acoustic pressure at a plurality of locations near each of a plurality of noise source panels;

for each of the plurality of noise source panels, reconstructing a surface acoustic pressure and a normal surface velocity on a source surface of the noise source based upon the measured acoustic pressures at the plurality of locations and reconstructing a normal component of acoustic intensity on the source; and

comparing a noise contribution from the plurality of noise source panels at a selected field point.

7. The method of claim 6 further including the step of comparing amplitudes and phases of the noise contributions from the plurality of noise source panels.

8. The method of claim 7 further including the step of ranking the contributions from the plurality of noise source panels.