Stereo Sound?

[Jay]

Stereo recordings often cannot be played on monaural systems without a significant loss of fidelity. Since each microphone records each wavefront at a slightly different time, the wavefronts are out of phase; as a result, constructive and destructive interference can occur if both tracks are played back on the same speaker. This phenomenon is known as phase cancellation.

- Wikipedia

Hmmm, now I'm really starting to wonder what Shannon has to say about this.