Sitting in a small airport, I noticed the voices around me - not for what they were saying but how things were said. The women to my left sounded like ducks, their voices rising and falling in a series of sharp, nasal jabs, debating something with an airline representative. Another group sounded like tires rumbling by on the highway, the coversation moving smoothly and quietly. One family sounded like a wind ensemble warming up - a few high-pitched tweets, an undercurrent of cello and a moment of harmony here and there.
I could tell the ducks were arguing, the tires were humming together and the family was chaotic but organized. All this just by the intonation as I could not hear the words.
It was the same small "aha!" moment I had when I realized that a smile can be "heard" over the phone (even if it's not reaching your eyes). It is what makes music so powerful. The melody and intonation of our voice can convey the main message - possibly better than our word choice.
That's not rocket science, I know. It's also not something we actively think about or practice beyond the moments when we have to do public speaking. Few of us are deliberate about intonation at all times.
"I have a great idea!"
"Let's start a lending library."
"We could do it with online and hard copy books."
Depending on the intonation in the above, even if the second speaker thinks they are conveying listening and openess, the subtext could be positive or negative. While the word choice/reaction is neutral, the musicality of the intonation will quickly give the first person a good indication even if the second person is trying to mask it.
We focus a great deal on words but little on other cues - especially in casual settings. Couple the music of our voices with our subtle body language cues and it doesn't matter what we say (good or bad).
The next time I'm trying to hold my impatience in check or my joy in bounds while choosing my words carefully, I'm going to listen to the melody of my voice to ensure I'm sending the message I actually intended to share.