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Sound and the NVH Team

Sound and the NVH Team. 2005 FSR / DSS Conference Terry Ryan & Mike Yost. Sound Fundamentals. To have Sound 3 things must exist A source A path A receiver. Source. Airborne sound will travel outward from its source. Sound reflecting off a structure will double. Wall of structure.

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Sound and the NVH Team

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  1. Sound and the NVH Team 2005 FSR / DSS Conference Terry Ryan & Mike Yost

  2. Sound Fundamentals To have Sound 3 things must exist • A source • A path • A receiver

  3. Source Airborne sound will travel outward from its source

  4. Sound reflecting off a structure will double Wall of structure.

  5. Wall or Fence. Wall of structure. Sound reflecting off these structures will virtually quadruple

  6. Structure Born Sound Transmitted from the SOURCE through a SOLID Object Structure acts like a Speaker Structure borne sound can be audible throughout a room

  7. and here There are windows here here Let’s take a moment to get a lay of the land. Here’s our outdoor unit. The Air Handler is in the closet.

  8. and here at this window. Does it sound similar outside? If all three places sound similar it’s likely airborne If it’s louder inside than outside, it’s structural The sound is the loudest in this wall here Listen at the wall here

  9. Can we hear the sound in this wall? We would if Structure Borne. If the sound is in the piping, you may be able to hear it here. At this point our Sound appears to be Airborne.

  10. Place a sheet of plywood here. If the sound level decreases, it was Airborne Sound.

  11. Airborne Sound“WAA-WAA” • Compressors having a synchronous speed of 3600 RPM (and loaded around 3300 to 3400 RPM) • The outdoor fan motor having a synchronous speed of 1200 (loaded near 1100). Multiply the number of blades on the fan (3) and we get it’s frequency of 3300. • The difference between the fan and compressor frequencies cause the beating “waa-waa” sound.

  12. Airborne SoundWAA-WAA

  13. Airborne SoundWAA-WAA

  14. Airborne SoundPlatform Acts Like Megaphone

  15. Structure Borne Sound

  16. Structure Borne Sound

  17. Structure Borne Sound

  18. Hydraulic Hammer

  19. Damaged Internal Springs

  20. Damaged Internal Springs

  21. Stethoscope: Looking for source of sound

  22. NVH Field VisitFiltered Beats Complaint 2/15/2005 Dave Renegar, Rick St. Mars, Jerry Hoover

  23. Master Bed Room on other side of wall (Where sound is objectionable) Line Set runs up wall into attic 1-1/8” + 3/8” 2A7A2048A1000AA 418479L3F Hard 90 brazed in-between brick & wall stud space

  24. First attempt by Installer • Compressor replaced once

  25. ISR0063 added inside unit and outside unit • Removed mortar from contact with line set

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