MBHO Jecklin Disc

What you are looking at is not an extraterrestrial spa-cecraft but a "Schneider disc". The Schneider disc is a variation of the Jecklin disc developed by Jürgen Jeck-lin for his stereo microphone technique known as Opti-mal Stereo Signal (OSS). The idea behind OSS is to use a pair of spaced omnidirectional microphones approximately 6 inches apart (roughly the distance bet-ween the human ears) with a disc placed in between the spaced pair. The disc is covered with a thin layer of foam intended to absorb high frequencies - thus impro-ving stereo separation between the microphones. The difference between the two types of discs is the foam sphere at the center of the Schneider disc, which redu-ces the amount of high-frequency energy reflected from the disc, and results in an increase of stereo separation.Below approximately 200 Hz, the Schneider disc has little (if any) effect on the stereo signal because the audio wavelength is large enough to bend around the
disc, equally reaching both microphones. However as frequency increases above 200 Hz, the Schneider disc's foam sphere increases stereo separation between the spaced pair.