Subliminal messages are self-hypnosis tools with voice-recorded messages masked by other audio--usually soothing music or nature sounds. The recorded messages are inaudible to the conscious mind, but may be perceptible as strong suggestions to the brain's unconscious mind. Pre-recorded CDs with subliminal messages are available for smoking cessation, weight loss, boosting self-esteem and more, but you can create your own personalized versions at home.
Compose your subliminal message. Keep your message positive (use "do" instead of "do not") and focus on one specific behavioral change. For instance, for a message to help you quit smoking the recording may be a simple directive like "you no longer want to smoke" or a more creative narrative about throwing out old packs and going about the routines of the day without a single cigarette.
Record the subliminal message using the voice recorder, maintaining consistent tone and volume. You can use your own voice or have a friend with a smooth and soothing voice record the message. You can also have a computer the message out loud and audio record it if you don't have access to a voice recorder of your own.
Upload the new voice recording to your computer, along with the masking audio track of music or nature sounds. The best masking audio is continuous sound that stays at a fairly constant volume and doesn't break between tracks.
Open the masking audio and your subliminal voice recording file with the audio editing software on your computer. Most audio software will allow you to open these files as two separate tracks on the same piece. Label the tracks "masking track" and "message track."
Lower the volume on the message track so that it is barely audible. The volume on the masking and message tracks should differ by about 15 decibels, although this may vary. Set the message track to start five minutes after the masking track starts, The five minute time lag will give your brain time to relax before taking in the subliminal message. Loop the message track so that it continues through the duration of the masking track.
Export your finished subliminal message as a digital file or a burn it to an audio CD.
You may need to re-adjust the volume of the message and masking tracks depending on how the audio blends. This usually requires a few full listens to the completed track.
According to websites Snopes and StraightDope, science is inconclusive as to how effective audio subliminal messages actually are or whether they might simply demonstrate, at best, a strong placebo effect.