Acoustic Equipment Research Utilizing a Vacuum Chamber

A hearing aid company designs, manufactures, and assembles sophisticated acoustic parts such as special microphones and speakers. In order to test the microphone and speakers which go into hearing aids, as well as fully assembled hearing aids, it is imperative to know at which point the failure happens. Does the failure happen due to elevation or due to improperly designed and built hardware or software?

To eliminate any acoustic sound entering the microphone or emitting from the speaker, a vacuum chamber is utilized. Sound does not travel in vacuum since sound is simply vibration of air molecules. By pulling the chamber down to a vacuum of less than 100 millitorr, any exposure to background sound sources is eliminated. The only thing that is left is sound generated from electrical sources such as improper circuit design or background radiation. This also helps to determine how sophisticated audio equipment interacts with wireless internet signals or cellphone signals. There are countless sources of noise or electrical feedback which can cause the hearing aid device to fail.

Fortunately Acrylic Vacuum Chambers that are clear and transparent will enable to acoustic development engineer to perform high integrity testing on hearing aid circuits and assemblies.

You are looking our custom made vacuum chamber, 12 inch cube, top load model with a spring supported lid. There is also a small through hole which was drilled to enable to experimenter to run wires from the outside to the inside. We were not able to use a vacuum feedthrough as the requirement was that we could not cut the testing wires because cutting the testing wires would create electrical noise and interference. At this point, the experimenter will plate a Buna-N film, over the hole, then she will run the electrical wire through the Buna-N hole and through the hole drilled into the side wall of chamber.

Did it work? Yes, we were able to get a good seal and pull the vacuum down to less than 0.1 Torr. Sometimes additional Vacuum Grease was used to seal some leakers. The experimenter was able to go down to specified 0.075 Torr and stay at that level for some time in order to complete their analysis.

Are you conducting tests on high performance acoustic and electrical circuits. Contact Us to see how we can make your experiments better.

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Altitude Simulation Systems
Altitude simulation systems are devices that simulate a certain altitude equivalent by controlling the vacuum inside a vacuum chamber. Altitude is a function of absolute pressure, therefore if a certain pressure is accomplished inside a vacuum chamber, a specific altitude can be simulated from the set pressure. Altitude simulation systems can be configured to not only hold a certain pressure, a complete pressure vs time profile can be programmed to be run. Furthermore, pressure vs time recipes can be loaded and run based on test requirements.
Ethernet Vacuum Feedthroughs
Ethernet Vacuum Feedthroughs are Vacuum Rated Ethernet connectors that enable you to run ethernet cables into your vacuum chamber. Simply connect your ethernet connector to the outside of the vacuum chamber and another ethernet cord from the inside and run it into your part present inside your vacuum chamber.
Our Work: Vacuum Testing of Lithium Ion Batteries, Thin Film, Fuel Cells, Supercapacitors, and Nano materials
This vacuum chamber is a modification to our basic acrylic vacuum chamber 12 inch, removable lid model; except that our customer requested additional ports and electrical feed-through for testing of electrical equipment under vacuum. You know, I wish we would have asked them for more details on what they were doing with this chamber; their short and concise answer was that they were using our chamber to perform scientific work on the subjects of: lithium ion batteries, thin films, fuel cells, super-capacitors, and nano-materials testing in a vacuum environment.
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