10khz line

The 10kHz line is a distinctive audio signature found in recordings from the German radio station NDR during the 1980s. This confirmed the origin of the recording of The Most Mysterious Song On The Internet, meaning that it was indeed broadcasted by NDR.

Discovery and Explanation

This line was discovered by user Fliere and reported in a Reddit post on January 29th 2021.

The 10kHz line refers to a specific attenuation or dip in the frequency spectrum at around 10 kHz. This was characteristic of NDR broadcasts and has been confirmed through the analysis of multiple recordings from this station during the era. The line is no mistake, it seems to be a byproduct of the broadcast equipment or modulation technique used at the time.

There was some speculation as to whether the 10kHz line could have resulted from a known phenomenon called Sporadic E layer propagation, which might affect radio signal transmission and reception. However, the consistency of the line across a wide array of recordings indicates this is a static NDR specific feature.

This discovery proved that Darius, the person who originally recorded the song from the radio, did not record The Mysterious Song from another station, such as Hilversum 3, as well as confirming other tracks on the tape that also aired on NDR.