Ready to hear some trippy stuff? Check out these audio illusions from Diana Deutsch (of Sometimes Behaves So Strangely fame). Explanations for each illusion are at the bottom the post. All the audio and explanations come from Diana Deutsch's Audio Illusions site, where you can check out her CDs for more brain-bending tracks. And let us know how it goes -- leave us a note in the comments section.

Chromatic Illusion

Ready to try this puppy out? Put your headphones on (you won't get the right effect if you listen through your laptop or computer speakers... unless you have external stereo speakers that you can separate and place on your left and right sides):

• Do you hear higher tones in one ear and lower tones in the other ear?
• What happens if switch your headphones to opposite ears while the pattern is playing?

Cambiata Illusion

This illusion works best with headphones, with the volume kind of soft:

• Do you hear higher tones in one ear, and lower tones in the other?
• Which ear hears higher tones?
• Try flipping your headphones (so they're on different ears). What happens to the tones?

Phantom Words

To get the full effect, play this through some stereo loudspeakers -- they should be separated as much as possible, and placed in front of you with the left speaker to your left, and the right speaker to your right:

Mysterious Melody

Listen to this -- you know this song, but it's maddeningly unrecognizable. The notes and timing are all correct, but the octaves have been scrambled:

Explanations

Chromatic Illusions:

Here's a brief explanation of what's probably going on in your ears:

When the pattern is played in stereo, many people hear a higher line that moves down an octave and up again, together with a lower line that moves up an octave and down again, with the two meeting in the middle. Yet when each channel is played separately, it is heard correctly as a series of tones that jump around in pitch ... When played through stereo headphones, righthanders again show a tendency to hear the higher tones on the right and the lower tones on the left, but lefthanders as a group are much more variable in terms of what they hear.

Read more, and take a look at the musical notation of what you think you're hearing, versus what's actually being played.

Cambiata Illusion:

Below is what most people hear, though not everybody (read more at Diana Deutsch's Audio Illusions):

Many people experience the illusion of a repeating higher melody in one ear, together with a repeating lower melody in the other ear. (Both these melodies are called 'cambiata figures'.). When the earphone positions are reversed, people often hear the same thing: The ear that had been hearing the higher melody continues to hear the higher melody, and the ear that had been hearing the lower melody continues to hear the lower melody. This produces the strange impression that the higher tones have migrated from one earphone to the other, and that the lower tones have migrated in the opposite direction. As another strange thing, righthanders are likely to hear the higher tones on the right and the lower tones on the left, regardless of how the earphones are positioned. But lefthanders as a group vary considerably in terms of where the higher and the lower tones appear to be coming from.

Phantom Words:

Some of the words and phrases people have heard while listening:

window, welcome, love me, run away, no brain, rainbow, raincoat, bueno, nombre, when oh when, mango, window pane, Broadway, Reno, melting, Rogaine

People tend to hear words related to what's on their mind -- according to Deutsch, if you're hungry or on a diet, you might hear words related to food. Other strange effects: you might hear the voices morphing into unusual accents, and you might hear words in another language if English isn't your first language.

Mysterious Melody Unscrambled

Give up trying to put your finger on the melody above? Here it is, demystified: