We discovered these when thinking about optical illusions where a picture can be seen one way, and then seen a different way. We were unsure of what to call them, originally thinking of the term "aural illusions," until research yielded the discover of "phonetic transpograms" on the National Puzzlers' League website. That really saved us. We recommend you say the word over and over on repeat, and let your mind drift from thinking about one word to the other.
TARGET - GUITAR
EAGLE - LEGAL - GULLY
KISSER - CIRCUS
SERPANT - PINCER
TURBO - BOATER
STORY - RESTORE
SAUCY - SEESAW
BETA - ABATE
DEMON - MINDY
MANURE - NORMA
FEMUR - MURPHY
WELFARE - FAREWELL
ROSY - ZERO
LISTEN - SINLESS
SULTAN - TINSLE - INSULT
PERSUE - SUPER
NURTURE - CHURNER
LADY - DELAY
CURSING - SINKER
RECENTS - SENSORY
SONIC - EXXON