Stereo Difference of Songs

Subtract the right channel from the left channel and see what you hear.

Most songs have purely mono content (usually the main voice) added on to stereo music and chorus voices. When you subtract the left and right channels of the final mix, the mono content completely vanishes, and you hear the difference of stereo material.

Winamp: In DSP/Effect, enable Nullsoft Signal Processing Studio. Load the "justin - stupid stereo voice removal.sps" preset file.

Cool Edit Pro 2.0: Effects (menu), Amplitude (submenu), Channel Mixer (item). Choose the "Vocal Cut" preset.

Samples

• Title: Little Wish ~lyrical step~
  Artist: 田村ゆかり
  Album: 魔法少女リリカルなのは
  Original sample
  Stereo difference sample

Observations

Pop songs are very amenable to this technique. Often, the main voice disappears and some instruments disappear as well. It can reveal instruments that were hidden by louder ones in the original stereo mix. Note that you can sometimes hear a soft reverberation of the main voice after subtraction, which means the reverb is stereo.

The stereo difference of orchestral music usually doesn’t result in anything interesting. This is probably because they are recorded straight without doing lots of funny editing ("heavily produced").

Lossy Compression

For MP3, the full stereo mode preserves stereo difference the best. Mid-side joint-stereo is pretty good. Intensity stereo by definition erodes the fidelity of the stereo difference.

For Vorbis, there is a sharp cutoff between full stereo and "sparse" stereo, at settings lower than q 8 or so. (image)

When comparing two (or more) lossy compressions of the same audio data, it’s good to also look at their stereo differences.

Links

• Subtractive Cancellation of Audio

Last modified: 2007-10-18-Thu
Created: 2007-04-24-Tue