Anechoic Chamber Equations and Polar Patterns
The tour group met up at National Technical Systems at around 11:20 AM, attempting to arrive early for the tour to allow them time to go through the host facility's sign-in process. Upon their arrival, the group met up with James Grosik, the head engineer of the facility, who welcomed them and thanked them for taking interest in the facility. He led the tour group through the different testing areas on their way to the chamber in question, briefly drawing their attention to different machines throughout the facility, describing the various types of durability tests performed at NTS using vacuum chambers, weather simulators, and other various devices used to push products to their limits. When the group arrived at the chamber itself, they were left in the care of Dr. James Vogler, the EMI Manager and Senior Scientist at the facility. Dr. Vogler had prepared some material for the group after the preliminary meeting arranging the tour, and he recounted some of the points of discussion from an earlier visit. The highlights of this discussion included his invention of a dual-capsule microphone designed to record with the Blumlein technique, and how the use of phase shifting allowed one to aim the stereo image of the sound after recording, as if you had re-positioned the musicians during the performance. He also discussed a special type of preamp he had created, which reduced the noise level of a signal by looping positive feedback back into the signal path to induce cancellation. The tour group remained in the chamber, noting its surprising lack of noise despite the presence of metal flooring. At 1:00, however, a scheduled client arrived for Dr. Vogler, and the tour was forced to draw to a close. The tour was dismissed, and the group left the facility at around 1:15 PM.
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