Gustatory / Auditory synaesthesia - The sense of taste is involuntarily stimulated in reaction to sound.  This is one of the less common examples of a synaesthetic strain and I have absolutely no idea how many people experience it.  I personally have been searching with varying degrees of enthusiasm since 1981 when I first discovered that synaesthesia was a recognised condition, and I've "found" only 13 others who share the same or similar "synsations" as myself.

Specific types of  synaesthesia are usually named according to the sense being stimulated first (Gustatory), and then naming the sense that reacts (Auditory).  With me, my taste sensations are automatically stimulated by my hearing.  I experience a very specific flavour, texture and sometimes temperature in a specific part of my mouth when I hear certain words or word sound