I composed this piece of music with a confident intention to deceive/trick the brain through music. As we know, music is a kind of frequency before being delivered to our brain. Actually, once one's brain gets this frequency, one can realize the pitch of the sound. In my music, I make one frequency (tone) to be played continuously, so the brain which listens to my music can experience the repeated procedure to be heard only one frequency ("D"). During this procedure, the brain may expect the repetition of the same frequency but, at some time, probably loses it since the other elements, such as the interval-relation, overtone, tritone, rhythm, may attempt to hide the very frequency.
If my music is efficient to show my point, the brain may face the situation of the both-sides repugnance not only the repeated frequency lost from the score during the music playing but also the frequency played in the ear after the end of music. Eventually, it is "Hide D" that I willingly attempt to compose the same kind of music as exposes the very conflict phenomenon.