As a child, I was blissfully unaware of synaesthesia. My world was a world of books/literature, language. Writing, classical music, pictures, people ... quite a rich childhood in terms of experiences and the senses. But it was there, part of growing up and the way I looked at, heard, touched and perceived the world around me.
I never thought consciously about it, but I knew I was different. It was clear to me that when other people described colour, they were doing it inadequately: they never described the shape and feel and temperature of a colour. I knew as a child that the power of music was absolute. Even as early as eight or nine, music could reduce me to tears because the experience was total - and totally devastating sometimes by its enormity, its sheer pleasure, its hurt.
I learned to play the piano and the violin but since I could not play well immediately, it was a bad experience for me. The sounds I made were uncomfortable at best and painful at worst. The violin was physically difficult to hold and the totality of the experience was bad.
By my teenage years I had read enough: I was aware of language and colour and symmetry - very important - in all the senses. Poetry and pictures and music were a "melange" for me. A mix I only began to understand when I read Baudelaire's wonderful poem "Correspondances" when I was about 17.
By then, life was more interesting, hormones jumping, horizons broadening and all the time I became more and more aware of my "powers". I didn't actually tell anybody: I knew it was unusual to say the least. For many many years I ignored the synaesthesia. I loved it, I exploited it, but I chose to ignore it in terms of telling anyone.
My wife - I eventually discovered!! - had noted the "odd" comments from time to time. When I described a glass of very good Burgundy as being "like drinking red velvet curtains", she attributed it to an imagination and a certain alcoholic euphoria! Stone cold sober, a glass of Volnay can even smell like red velvet curtains! To me anyway.
And so it continued over the years: a painting here, a rug there, my dog - each had a unique and multi-sense character. I do not own a "black labrador" - in addition to being all the things a dog is to his master, he is a combination of colour and shape and smell which do not follow the conventions. The "black" feels good to my eyes - and only another synaesthete can understand that I think - and the smell of a wet labrador has a unique feel to it, without touching the wet fur. This is not a learned and programmed sensation. It varies from day to day and experience to experience.
Music is the BIG one: the rich splendour of the Baroque is a colourful and sensuous I DON'T KNOW WHAT! I listen to a Bach Toccata and hear a kaleidoscope of colour, feel a multi-dimensional form, covered with texture from the smoothest silk to the pitted quality of an egg-box. It can be exhausting and addictive. It is also incredibly synaesthetic in that to separate the sound from the colour from the feel from the temperature from the body sensations is quite impossible.
The extent of the totality has on occasions been so great that I have had to stop what I was doing simply to sit down. On one occasion we were driving across western France, a wonderful June morning, blue sky, warm, along straight empty roads south of the Loire and we had some Händel playing. I was totally overcome by the sheer joy of the richness of everything. I had to listen to the end of the CD and I was virtually incapable of movement because of the total nature of the experience. A true concatenation of the senses.
Food and drink are part of the kaleidoscope: the taste of food is often colour based, and vice versa, and the taste takes on a 3-dimensional form in my mouth/brain. A cup of good coffee has a range of experiences: the simple taste and temperature collide with colour and feel and are transposed into "mixture" - that is one of the few things I cannot describe at all. I love good coffee!!
Today is not a good day for describing the experiences! Probably the simplest description I can give is that to be a synaesthete - in my terms anyway - is to experience life through, in and beyond a magnificent stained glass window, which in itself has colour, shape, depth, texture, shafted with sunlight, shadow and more. In the same way that the same window has superb qualities even on a dull day, I have a range of "quality", but it is rarely one quality which excels or lacks. A "good day" has the whole lot at full volume - colour, shape, taste, texture - and a "poor day" has rather less.
There are days when the whole lot goes down - like a crashed computer. They are disappointing times compared with the richesse of normal experience and sad when compared with the enormity of a really good day! They are rather black and white days, or parts of days.
Strangely I rarely remember coloured dreams, though often sound and texture figure there. As far as I am aware the dreams are as synaesthetic as daily life, but muted. Too exhausting to dream "totally"!
Alcohol has a pleasant effect normally but since I consume only moderately, I perceive little change, only exaggeration and then muting. I have never used any mind-altering drugs for the obvious reason: I don't need to take anything to get High!!
At this point I have just changed the colour of the document: The standard Black text was becoming uncomfortable - not to my eyes, but totally uncomfortable for me as a person. Dark blue is more "rounded". I frequently change the type face I work with: some can "hurt".
I find musical instruments normally - but not rigidly - have their own colours and textures and combine to make other colours and textures. The most "total" music experience is the Organ - for the obvious reasons. Anything from early organ music to the magnificence of Messiaen is a range of feelings, sounds, shapes, textures of a kaleidoscopic nature ranging from the calm to the orgasmic. The symmetry and asymmetry of J. S. Bach is the ultimate in synaesthetic experience for me, along with bits of literature which are devastating in their effect.
The human voice has the same range of qualities and sensations. Do you know the remarkable voice of Andreas Scholl, German counter-tenor? Andreas Scholl has a voice which I can only describe as being "pro-synaesthetic" in that it switches on instantly the whole range of mixed senses! There is a parallel in the American counter-tenor, David Daniels, whose skill and voice are the equal of Scholl's, but the voice lacks the silver-gilt quality Andreas' has, and has no "on" switch for the full experience.

A radio programme some years ago re-awakened my conscious interest in the subject and my wife saw the effect the programme had on me as we listened together. I "confessed" all. She did not send for the Doctor but listened and asked intelligent questions which were of course "silly" to me, but she hears things, sees things and touches things individually - unlike me! Since then she has understood more of what happens to me and occasionally asks what colour the music is - though she still does not appreciate the "red velvet curtain" nature of a glass of good Burgundy!!
I confess: few others have ever been told and those I have mentioned it to have shown little interest or a passing interest in the matter. Since I have red hair ...! Sensitive! If they did but know how robust a synaesthete has to be to survive the onslaught! Too tiring to explain!