Scientists have discovered that there are music and phrases that you come into contact with all the time that don't actually exist. The reason is due to your brain forcing you to hear sounds that should or ought to be there but aren't. You may be familiar with this phenomena through another sense: Sight. Optical illusions use similar tricks on the mind all the time. Illusions do this by making your brain fill in the voids. Our eyes also have a “blind spot” which our brains actually fill in with visuals despite the fact that our actual eyes can't see that particular spot. This is the same way the ghost sounds work, by creating an illusion of what should be there when it really isn't. They do it by using “Phantom” sounds. One of the studies that has added to this field of reasearch is from the University of California by Diana Deutch and it has been repeated since.

Phantom music occurs when we hear songs that are played at a high speed with groups of notes that are played in a repeating pattern or in arpeggios (Arpeggios is when a group of notes don't play at the same time but individually). The Phantom melody happens when the pattern played has a few stray notes that aren't supposed to be part of the pattern. Our brain naturally picks up on the stray notes and puts them together to form some kind of independent melody that doesn't really exist. Basically what’s happening is your brain is dismissing the repetition it understands and stringing together the notes that it doesn’t expect to make sense of the sounds around it. But if the music is played slower the melody vanishes from musical composition because it takes too long for our brain to see it as part of the melody. So imagine you hear a song playing DUM DUM DUM. Now if this is played fast repeatedly and the guitar player's finger hits the wrong string or the piano player hits the wrong key and we hear DUM DUM BING DUM and then right after it another mistake such DUM DEE DUM DUM are brain will naturally place the BING and the DEE notes together to form some kind of melody that isn't supposed to exist.

This concept gets even weirder when you consider what happens when the sounds aren't musical notes but just people talking. If we have a repeating string of words or even phrases overlapping each other in different parts of a room then soon you'll start hearing ghost phrases that aren't really there. Your brain is making them all up for you and you're believing everything it says. But can you blame your brain? It's confused and dis-oriented and trying to regain some kind of balance or piece of information that can get you out of its current state. For example, imagine your in a room and from your left you hear “tree, glass, tree, glass” and on your right “friend, compost, friend, compost” each phrase repeated over and over at the same time so that it's hard to distinguish them at first. You may think you hear something about your “friend” Joshua is going to plant a “tree.” Or whatever you subconsiously want to hear. Because your brain will tell you what's on your mind. So if for example you work in a recycling plant you may hear about the importance of “composting” while if you're best friend committed suicide you may think about how your “friend” did it with a piece of “glass” or hung himself from a “tree” (Gruesome topic added for emphasis). If we miss parts of the phrase our brain will fill in the blanks of what should be there. Even if it's not even a word but a chair squeek or a foot tap our brain will still change that sound to fit the rest of the phrase. And if you're foreign, for example Spanish, then any of the words could end up sounding like a foreign word you know so “tree, glass” could turn into “uno taco.”.