So I was listening to one of my favorite tracks from Lord of the Rings, "the breaking of the fellowship" and in some instances I heard a high pitch continuous ringing. Well that's odd that there'd be a recording artifact in the master of a highly acclaimed soundtrack. I didn't suspect it was an encoding issue as it was a lossless flac. I suspected it may have been a problem with my CD as it was bought soon after release, so I pulled up the song on amazon streaming, sure enough it was still there. So I pulled up the song in Adobe Audition, boosted the amplitude of the song 40 db and scoped around the spectogram and sure enough, there is a ringing throughout the song at 15.63 kHz. I discovered it was also in all other songs for all the Fellowship of the Ring. Well that's very odd indeed. So I pulled up a song from "The Force Awakens". Sure enough, there was a ringing there too however at a slightly different frequency of 15.73 kHz.
Well some poking around led me to these frequencies aligning with the horizontal scanning frequency of CRT televisions. Lord of the Rings, which was recorded in Abby Road Studios in the UK had a ring at 15.63 kHz which aligns with the PAL system scanning frequency of 15.625 kHz and the Star Wars sound track which was recorded at Sony Pictures Studios in CA aligned with the NTSC system scanning frequency of 15.734 kHz. Mystery solved!
Poking around in some of my other music reveals that it is commonly in final recordings, up there where most people probably won't notice. I suppose it is common to have a CRT somewhere in the recording studio that the mics can pick up. In most recordings all lower sounds mask it so it doesn't matter so much. However I have no clue why these recording studios don't notch filter it out when it's obviously there. It just takes a notch filter with a Q of 10,000 to remove it, and 100 Hz missing up at 15 kHz will never be missed. Any one else notice this in recordings?
