Linux Multimedia Hacks

Search Audio for Hidden Messages

Use a simple effect from the SoX play tool to check audio for hidden messages.

Backward messages in music (or “backmasking”) have provided quite a bit of controversy over the years. Music from the Beatles in particular has been popular to listen to backward in hopes of discovering hidden messages (one of the most famous being the phrase “Paul is Dead” at the end of “I’m So Tired” from the White Album). Since the Beatles, there have been numerous claims that music from a number of musicians contains hidden messages that are heard when played backward—messages that contain references to Satan, other evil things or, most commonly, drug use.

Of course, back in the days when most people listened to music on records, it was relatively easy to listen to a song backward—you just rotated the record on the turntable in reverse. This method won’t exactly work (or at least not easily) for tapes or CDs, but for digital content, Linux has just the tool to aid you in your search for backmasking—the SoX tool and its frontend called play.

SoX is a universal sound sample translator and allows you to format audio with a number of interesting effects. SoX provides two frontend applications, play and rec, that make it easier to play and record audio, respectively (the rec frontend is discussed in [Hack #33] ).

SoX is a popular program and should already be packaged, and possibly even installed, by your distribution. If not, you should be able to install it using your distribution’s ...