I have had synesthesia since I was, I guess, born. I didn't find out until I was ten that this was not something everybody experiences. It is impossible for me to not associate a sound with an abstract visual image, not that I don't want to, except a few times when I have meditated on sounds. I have tried to meditate on sounds and just experience the sound, but when I do so I seem to come closer to seeing that my sensation of the sound and my experience of the associated visual image are exactly the same experience.