sound deadening, professional project

Hello, my name is Anthony, I am a representative from Michigan Technological University. At this university, a group of undergraduate students, graduate students, and faculty have come together to find immediate solutions to modern day vehicles to improve performance and fuel efficiency. In an effort to do this, my job is specifically geared towards vibrational analysis, sound deadening, and overall customer satisfaction. Using some extended resources, I was directed here for some assistance. The car is a 2008 Chevy Equinox. My goal is to find the best performing sound-deadening material for the most inexpensive cost, as well as ideas for which areas in the car could use increased sound deadening. Some current cars that have come out boast "silence within the cabin" even in the midst of bells, clocks, and extreme noise going on outside the vehicle, but advertise the cabin as being silent. If you can offer any insight on this technology, or how it can be rivaled on a production budget, please let me know. I am just trying to collect some ideas on where I should start, including what materials in what amounts and in which places. Thank you, Anthony EE - Michigan Tech University

Somewhere there is a review of different types and brands of sound deadening materials. Also had a white paper from a company that supplied airplane manufactures with vibration/noise materials. Either might be helpful. I will see if I can find them. Something else to consider is noise canceling technology. Same concept as the headphones. In office buildings we use a measurement microphone to find the annoying frequencies, process the signal, then spit it out through a speaker. Basically flipping phase to cancel. It works well for constant noises such as air handlers. Thinking exhaust, engine noise, you get the idea!

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audiocableguy wrote: Somewhere there is a review of different types and brands of sound deadening materials. Also had a white paper from a company that supplied airplane manufactures with vibration/noise materials. Either might be helpful. I will see if I can find them. Something else to consider is noise canceling technology. Same concept as the headphones. In office buildings we use a measurement microphone to find the annoying frequencies, process the signal, then spit it out through a speaker. Basically flipping phase to cancel. It works well for constant noises such as air handlers. Thinking exhaust, engine noise, you get the idea!

Hey audiocableguy, those are some great ideas. I look forward to hearing what materials you were using to help with vibration and noise. I am especially interested in the technology that you spoke of, especially the digital signal processing (DSP) necessary to find the frequencies to which you were speaking of. Can you help lay out for me some of the DSP steps that you took in order to process that signal and then how you used phase changing as a filter? Lots of thanks, Anthony EE - Michigan Tech

I found where Toyota has already applied the noise canceling technology to a Hybrid. I will send you a PM when I get home.

Thank you very much! I look forward to it! -Anthony EE - Michigan Tech

Well, the rest of the group is working on reducing the overall weight of the car by changing parts and components with those of lighter weight without impairing performance. Of course my true goal is to find a sound deadener that weighs less than that of what is stock that offers better performance and is less expensive. If I could find such a thing, it would really help me bolster the vehicle. Of course the noise-reducing technology as aforementioned would of course be pivotal and a major boost to the project in its entirety. I will investigate the links you gave me and I will report back with more information. Thank you, -Anthony EE - Michigan Tech

Here's where somebody has already done all the digging! A really good resource, and I discovered it after I damped the entire interior of my Civic with five full boxes of Dynamat Extreme. A box is 39 square feet. There is one full box in each door, and the difference was astounding! The point no return can come quickly, however, as each layer placed will require TWICE that amount to double the damping efficiency; i.e. for one layer, you gain 3dB of quieting, for 6dB, you must have three layers. stevdart mentioned the lack of economy improvement, and considering the weight necessary to GET proper damping, an overall decrease will be far more likely. Many high-end cars will use double walled firewalls, damped with sand... Hardly fuel efficient, there... My personal opinion is that the most expensive and potentially the most EFFECTIVE way is the way to go - Active Noise Cancellation.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Any information on the active noise cancellation system? I am very well aware of how Dynamat Extreme works, but I also have recognized what everyone else here has, and that is the weight issue. I am glad that you have done a lot of digging yourself, but have you any insight on how the active noise cancellation system works? Any ideas of where to start? Thank you, Anthony EE-Michigan Tech