The problem is, the type of synaesthesia I encounter is heavily colour-oriented. This is a problem due to my colourblindness and a lack of a test capable of fully diagnosing my condition without being reliant on true colour perception.
Colourblindness is another thing that is largely misunderstood. Most people I have discussed synaesthesia with haven't even heard of it but most are aware of colourblindness even if they are ignorant of the true meaning of it. The response tends to be 'Oh, you're colourblind? What colour is this then?' *holds up random object*
More militant or irritable colourblind people have been known to follow that question up with another question, along the lines of 'if I were in a wheelchair would you ask me to stand?' I don't go in for that sort of histrionics but it is a sort of a disability in that it's something that I and others can't do that most people can.
I took the test, but failed. I don't have synaesthesia. But I am colour vision deficient. Not too badly, but it does affect me. They have labelled me as red/green colour vision deficient. But I wish there was a better way to define it in this day and age. For me certain shades of green, brown, orange all look identical. I would love to find a way to define an envelope of the colours I can't distinguish, say in the RGB number system.
Often, when I don't know what a colour is, or when I am trying to match up colours so they are the same, I will use Photoshop and find out the RGB values. Is it possible you can do something similar, when you see a colour and hear a sound, you can take a photo of that colour and break down it's RGB value, then note the sound? Maybe that word start to form a pattern - maybe even help you know the colours you are seeing because of the sounds you hear...