Throughout history humans have used the nuances of voice to understand one another. We understand instinctively what we really mean by the little jumps and stops and changes in tone and pitch and volume of our voices.
My interest in the topic started back in school days when the school choir was competing in a big competition and we were all very careful to keep our voices in order through the months of practice for the big day. I noticed all the things affecting our voices, and very little was about catching a cold.
