CD players typically have a mechanism to detect these hidden tracks. Some CD players will automatically play the hidden tracks, while others require you to press a specific button or perform a certain action to access them.
Here's how hidden tracks are created:
1. Pre-gap tracks: Hidden tracks are often created using pre-gap tracks. A pre-gap is a small gap between the tracks on a CD. In the case of hidden tracks, the pre-gap is used to hide the hidden track. The hidden track is placed in the pre-gap, and the CD player is programmed to skip over the pre-gap when playing the CD.
2. Subcodes: Subcodes are special codes written onto a CD. These codes tell the CD player which tracks are playable and which ones are not. In the case of hidden tracks, the CD player is programmed to ignore the subcode for the hidden track.
3. Absolute time addressing: Absolute time addressing (ATA) is another way to create hidden tracks. With ATA, the CD player is programmed to track the exact time when the hidden track begins playing on the CD. This allows the CD player to stop playing the CD at that exact time, effectively hiding the hidden track.
Hidden tracks can add a fun and interactive element to CDs, allowing artists to provide extra content to their fans. They can also be used to include hidden messages or secret songs.