I don't hear, Atheist. I see. Your words in the post I mentioned created in my mind flashes of colour and movement. That for me brings your words to life and I then see pictures that you have painted with your written word to the point where I could believe I'd experienced what you had.
All my words and numbers have a colour. When people speak to me I see the colours of their words. Some much stronger than others. Nouns are always very strongly coloured.
When I close my eyes I never see dark. I see colour and pictures. The pictures are a bit like watching a film. I see people, animals, places....no idea about any of them and luckily I can fade them out if I choose but I find them fun mostly and interesting because I don't know what is going to appear.
So while, as a synesthete, some of my senses merge, taste and hearing don't. Some people have a merging of all five senses. That must be weird!
I was in my thirties when I discovered that not everyone saw things the way I do and that there was such a thing as synesthesia. It came as quite a surprise. The conversation with bewildered Mr and MissG about what colour Tuesday was still makes me smile. You know.... when folk are looking at you as if you've gone mad!
But I'm happy to be a synesthete.... :-)