Mei Wu Acoustics

Research

Mei Wu Acoustics emphasizes learning, researching and developing new techniques with each project and assignment.

Speech Intelligibility in Teleconferencing

We have developed a program that predicts speech intelligibility, based on:

  • acoustical treatments in the source room and the receiver room,
  • ambient noise in both rooms from HVAC as well as people,
  • location and orientation of the speaker, and
  • location and directivity of the microphones.

After testing, we have found that the program's predictions agree with site measurement results.

Airflow Noise Prediction

Low frequency rumble noise generated by turbulent airflow in HVAC duct is a common noise problem in modern large buildings. We have developed a program to predict flow generated noise based on air volume and air velocity, duct sizing and shape, and duct fitting elements. Using this program, we can determine if and how much flow noise needs to be mitigated.

Passive Silencer Insertion Loss Enhancement

Mei Wu developed equations to calculate the sound attenuation along rectangular silencers and conducted tests to verify the accuracy of the equations. Exceptionally high insertion losses were achieved at low frequencies by matching the acoustical impedance of the lining material with the frequency parameters of a silencer.

No-media Silencer Development

Mei Wu developed a micro-perforation silencer product line for a silencer manufacturer. She

  • developed equations for silencer performance prediction,
  • designed prototype silencers using these equations,
  • tested the silencers,
  • made modifications to perfect the designs,
  • finalized the designs, and
  • generated catalogue data.

After testing, we have found that the program's predictions agree with site measurement results.

Active Noise Cancellation for Small Axial Fans

Mei Wu designed an active noise cancellation system for a small cooling fan on simulated office equipment. Test results showed that the system generated a clearly audible global noise reduction at the fan blade passing frequency.

Machinery Noise Source and Transmission Path Identification

Mei Wu developed a modified cepstrum algorithm to determine the frequency response function of structures without any advanced knowledge of input signals. She conducted Computer simulated experiments and vibration experiments. The test results showed that frequency response functions recovered by the modified cepstrum technique converge to the actual response functions.

 

In addition to the above projects, we are also experienced in

Publications

  1. Mei Wu, Stewart He, "Automatic wireless sound monitoring system and its application at Caldecott Tunnel", presented at NOISE-CON 2011, Portland, Oregon, July 2011

  2. Mei Wu, Warren He, "Cost-Effective Wireless System for Large-Scale Noise Monitoring", published at Sound and Vibration, February 2011, p.11-13.

  3. Mei Wu, Slobodan Lukic, L. Zeng, "Floor Vibration in Laboratory Buildings", published at R & D magazine Vol. 51, No. 6, October 2009, p.18-19.

  4. Travis Lawrence, Mei Wu, "Acoustical Wall Design", published at Archi-Tech website www.architechweb.com in April 2009.

  5. Mei Wu, James Black, "Can You Hear Me Now - Effects of Physical Environment on Speech Intelligibility in Teleconferencing", published at Sound and Video Contractors website www.svconline.com in June 2005.

  6. Mei Wu, "Speech Intelligibility in Teleconferencing", Presented at April 2005 Meeting of Audio Engineering Society San Francisco Chapter.

  7. Mei Wu, "Fan Filter Unit Noise Specification and Prediction", Proceedings of ESTECH 2003, p.95-99 (article 2003).

  8. Mei Wu, "Effects of VFD�s on Roof-top Air Handling Unit Noise and Vibration Control", Presented at March Meeting of ASHRAR San Jose Chapter (2003).

  9. Michael Gendreau, Mei Wu, "Environmental Noise Control for Semiconductor Manufacturing Facilities", Proceedings of Inter-Noise 99, p. 1099-1104 (article 1999).

  10. Mei Q. Wu, Colin G. Gordon, "Noise and vibration characteristics of cleanroom fan filter units", Proceedings of the 16th International Congress on Acoustics, p. 771-772, (article 1998).

  11. Mei Q. Wu, Colin G. Gordon, "Noise of cleanroom recirculation systems", Proceedings of the 16th International Congress on Acoustics, p. 769-770, (article 1998).

  12. Colin G. Gordon, Mei Q. Wu, "Noise and vibration characteristics of cleanroom fan filter units", Presented at IEST Meeting, Phoenix, (presentation only 1998).

  13. Mei Q. Wu, "Micro-perforated panels for duct silencing", Noise Control Engineering Journal, Volume 45, Number 2, p. 69-77 (article 1997).

  14. Mei Q. Wu, "Active cancellation of small cooling fan noise from office equipment", Proceedings of Inter-Noise 95, p. 525-528, (article 1995).

  15. Mei Q. Wu, "A new technique for measuring structural dynamic response", The Journal of the Acoustical Society of America, Vol. 93(4), pt.2, p.2280, (abstract 1993).

  16. Mei Q. Wu, "Micro-perforated sheet metal and its application to silencer design", The Journal of Acoustical Society of America, Vol. 93(4), pt.2, p.2309, (abstract 1993).

  17. Mei Q. Wu, "No-media silencer design based on micro-perforation theory", Proceedings ofInter-Noise 93, p.1223-1226, (article 1993).

  18. Tom Paige, D. L. Allen and Mei Q. Wu, "Structural-borne noise control in the CBC Broadcast Center", Proceedings of Inter-Noise 92, p.109-112, (article 1992).

  19. William J. Gastmeier and Mei Q. Wu, "Sound transmission loss of demising walls and floor/ceiling assemblies", Proceedings of Inter-Noise 92, p.659-662, (article 1992).

  20. Mei Q. Wu, Tom Paige and D. L. Allen, "Optimum positioning of duct silencer in sound-rated construction", Canadian Acoustics, Vol.19, No.4, p.13-14, (article 1991).

  21. Mei Q. Wu, William J. Gastmeier and D. L. Allan, "Noise complaints in residential condominiums", Proceedings of Noise-Con 90, p.291-294, (article 1990).

  22. Mei Q. Wu, William J. Gastmeier and D. L. Allan, "Analysis of objectionable noise in residential buildings", the Journal of the Acoustical Society of America, Vol. 87(S1), p.S100, (abstract 1990).

  23. Mei Q. Wu and Malcolm J. Crocker, "A practical application example of the modified cepstrum technique", Proceedings of Inter-Noise 89, p.1207-1210 (article 1989).

  24. Mei Q. Wu and Malcolm J. Crocker, "Application of Gerchberg's iteration algorithm to noise spectrum restoration", The Journal of the Acoustical Society of America, Vol. 85(S1), p.S12, (abstract 1989).

  25. Mei Q. Wu and Malcolm J. Crocker, "The modified cepstrum technique for machinery monitoring", Proceedings of the 1st International Machinery Monitoring and Diagnostics Conference, p.79-85, (article 1989).

  26. Mei Q. Wu and Malcolm J. Crocker, "The properties of the estimation error of sound power measurement using sound intensity technique", The Journal of the Acoustical Society of America, Vol. 85(3), p.1182-1190, (article 1989).

  27. Mei Q. Wu and Malcolm J. Crocker, "A novel way of determining the structural frequency response function without any pre-knowledge of the input signal", Noise Control Engineering Journal, Vol. 32, No.1, p.43-46, (article 1989).

  28. Mei Q. Wu and Malcolm J. Crocker, "Structural response function recovery by the modified cepstrum technique", Proceedings of Noise-Con 88, p.511-516, (article 1988).

  29. Mei Q. Wu and Malcolm J. Crocker, "Restoration of the spectrum of a steady noise overlapped by an impulse", Proceedings of Inter-Noise 88, p. 39-42, (article 1988).

  30. Mei Q. Wu and Malcolm J. Crocker, "The application of the cepstrum technique to the separation of the input signal and the system response", The Journal of the Acoustical Society of America, Vol. 82(S1), p.S65, (abstract 1987).

  31. Mei Q. Wu and Malcolm J. Crocker, "The probability distribution of number of sound intensity measurements for sound power determination", Proceedings of Inter-Noise 87, p.1271-1274, (article 1987).

  32. Mei Q. Wu and Malcolm J. Crocker, "A statistical analysis of the estimation error of sound power measured by sound intensity technique", Proceedings of Noise-Con 87, p.601-604, (article 1987).

  33. Mei Q. Wu and Malcolm J. Crocker, "A statistical analysis of the estimation error of sound power measured by sound intensity technique", The Journal of the Acoustical Society of America, Vol. 80(S1), p.S119, (abstract 1986).

  34. Mei Q. Wu and Malcolm J. Crocker, "Effect of the number of measurements of sound intensity on the accuracy of sound power estimation", Proceedings of 12th International Congress on Acoustics, p.c8-1, (article 1986).

  35. Mei Q. Wu and Malcolm J. Crocker, "A computer simulated investigation of the estimation error of sound power measurement", Proceedings of Inter-Noise 86, p.1129-1132, (article 1986).

  36. Mei Q. Wu and Malcolm J. Crocker, "The determination of noise source and path properties by the cepstrum techniques", Proceedings of the International Conference of Vibration Problems in Engineering, p.540-544, (article in Chinese 1986).

  37. Mei Q. Wu, Hui-de Yang and Pei-jun Li, "Sound power measurement of diesel engines by the sound intensity techniques", Noise and Vibration Control, Vol. 4, p.2-7, (article in Chinese 1983).

  38. Song-ling Zhao and Mei Q. Wu, "Sound attenuation in rectangular ducts", Proceedings of the 11th International Congress on Acoustics, p.389-390, (article 1983).

  39. Chang-xuan Feng and Mei Q. Wu, "The calibration and application of Ono Sokki CF-150 engine analyzer", Presented at the 1982 Annul Meeting of the Society of Diesel Engine Measurement, (presentation only 1982).

  40. Song-ling Zhao and Mei Q. Wu, "The calculation of sound attenuation in a duct", Proceedings of the Third National Conference of the Acoustical Society of China, p.175-180, (article in Chinese 1982).

  41. Song-ling Zhao and Mei Q. Wu, "Sound attenuation in lined rectangular ducts in the presence of fluid motion", ACTA Acustica, Vol. 7(6), p.380-386, (article in Chinese 1981).

In addition to the above major R&D projects, Mei Wu has also worked on acoustical panel design, diesel engine exhaust noise control, large workshop noise modeling, environmental noise modeling, and finite element and boundary element modeling.