The sound of words in my head

I just noticed something this morning. Or, more accurately, I have always noticed it, but inexplicably payed it more attention this morning than before. When I read certain words, they make sounds in my head - not just the sound of the word, the way we 'read aloud' in our heads when we read. Certain words are accompanied by other sounds - almost without fail when I read them. The word that caught my attention this morning was:

"building blocks"

The word "blocks" often triggers a similar sound, but this combination is particularly strong. It sounds like wooden blocks I used to play with as a kid in my gran's house. Also the sound her parquet floor makes when you walk over a slightly loose block. There it is again... I can even smell the air in her house when I think about it and repeat the word a few times. It goes away when I try to force it though.