Discovering A Hidden Third Channel In Stereo Recordings
December 1, 2014
In some of my previous blog posts, I mentioned that I like to experiment with music. I’ve created a series of music and drumbeat montages, and I’ve also been able to uncover
hidden music and lyrics in pop songs.
I’d now like to share with you, a serendipitous discovery I made a while ago. While I was playing around with my audio editing software, I managed to uncover previously unheard vocals in some pop songs. To be fair, most songs yielded nothing of any interest, but one tune in particular was remarkable – it was almost as if I had discovered a secret “third channel” hidden in the stereo recording.
As we all know, almost all modern music is recorded in stereo. There was a time during the early 1970s when
quadraphonic sound looked like it would become popular, but it never gained widespread acceptance. More recently, the SACD (Super Audio Compact Disc) and DVD-A formats promised music in 5.1-channel surround sound, but
they never became popular either.
The source materials I used were neither quadraphonic nor surround. They were simply ordinary CDs, recorded in stereo. One afternoon, as I was extracting songs from CDs, and then playing around with the waveforms, I heard what sounded like brand new vocals and unexpected instrumentation on a 1977 song called
Long Time, by Boston. What was going on here? Where was this new material coming from?
Here is a short excerpt from the song. This is the original, unaltered version:
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This is the mysterious “third track” that I had somehow uncovered:
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I’ve been listening to this song for decades, yet I’ve never heard these vocal harmonies before. I then listened to both the left and right channels of the original recording, but I still couldn’t hear these new vocal harmonies. I wasn’t sure exactly how these vocals suddenly became isolated and audible, but I knew that this was significant. I quickly wrote down everything I had done, so that I wouldn’t forget the procedure. These are the steps:
- Isolate one channel, and invert the waveform. In this case, I inverted the left channel. These are the before and after images of the waveform.
2. Combine the inverted left channel with the normal right channel, into a mono signal. This is what it looks like:
Naturally, the next thing I tried to do was identify and extract a fourth channel. Who knows how much more material was hidden in these stereo recordings, just waiting to be uncovered? I was convinced that I was on to something big – this could mean the rebirth of quadraphonic sound. However, unlike the early 1970s quadraphonic recordings, which had to be recorded in four channels, I would be able to extract channels three and four from ordinary stereo recordings. Imagine experiencing your existing music collection again, in four-channel sound! I was already imagining an audio renaissance and the re-emergence of the audiophile.
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