Faces are as complex and distinctive as voices, but easier to describe. Why are we so inarticulate when it comes to talking about something so essential to our identities as the human voice? Most of us learn to speak by imitation, not by instruction. We know voices intuitively. We learned as infants to recognize and interpret voices long before we learned to speak. We don’t have to think much about what makes a voice unless we lose it or try to train it to yodel and sing arias.

In the winter of 1976 Mark Twain came to Cincinnati’s Music Hall in the form of Hal Holbrooke’s one-man show. My then-girlfriend and medical school classmate, who knew my fascination with Twain also as my refuge from my insecurities about surviving medical school, arranged for us to usher that evening. Luck left us with two empty seats in the 10th row, close enough to see his whiskers twitch and the smoke of his pipe curl.