gregg manderson , 68 , of st paul , minnesota , has auditory hallucinations .
he sought help for condition last may when lullaby twinkle , twinkle little star crept into his head .
songs , which have included police sirens , last for about a month , but for years he has heard a bugle call that could be linked to his time in vietnam .
manderson originally did n't know .
theme song to the 1950s western show cheyenne also often in his mind .