“I hear the sound I love,” Walt Whitman wrote, “the sound of the human voice.” In fact we all love the human voice and we respond to it, as to no other sound in nature, with bristling attentiveness, from the moment of our birth. The birds out-sing us; bats squeak in registers beyond our hearing; whales and dolphins communicate across the depths. But the voices of animals don’t possess the peculiar resonance of the human voice, which arises from the fact that our voices are at once generic and intensely individual. It’s true that a penguin parent can distinguish its offspring’s squawk in the midst of a rookery, and other birds and mammals share this ability; but this appears to be a reflexive mechanism rather than the expression of a personality. We not only recognize the voices of our children or friends or colleagues instantaneously; we know at once, often with pinpoint accuracy, whether they’re happy or sad, angry or anxious, or any of a thousand possible states of mind, even when they do their utmost to hide their feelings. Whatever their words may say, their voices say more.

Attuned as we are to the daily decipherment of innumerable vocal clues, we also possess an amazing repertoire of registers. Each of us has a distinctive voice, but we command dozens of other voices. My uncaffeinated earlymorning voice seems to issue from a different voice box than my mellower, late-afternoon voice.And these are but two of the “various carols,” to use Whitman’s phrase, I hear myself humming during the course of a single day. The phenomenon is emotional as well as physical; the voice is as nimble as a chameleon, shifting its acoustic tints in harmony with its surroundings. Nietzsche wrote, “When we talk in company we lose our unique tone of voice, and this leads us to make statements which in no way correspond to our real thoughts.” But this is only part of the truth. Do we know our “real thoughts” before we’ve voiced them?

In her fascinating new book, “The Human Voice: How This Extraordinary Instrument Reveals Essential Clues About Who We Are” (Bloomsbury, 416 pages, $24.95), British sociologist Anne Karpf details the current state of our knowledge about this inescapably familiar yet strangely neglected faculty. Ms. Karpf is a BBC broadcaster as well as a weekly columnist for the Guardian and so she not only writes clearly and succinctly but as a professional wielder of the human voice, she has a privileged vantage point. Even better, as a delighted connoisseur of the human voice, she knows how to listen; the interviews she includes with people from all walks of life are as intriguing as the scientific data she has gathered.

Ms. Karpf begins with the voice as a physical instrument, discussing such aspects as stress, pitch, volume, tempo, and timbre, all of which are essential to its effect. Along the way she provides startling facts; thus, “Saying ‘Hello, how are you?’ alone requires the coordinated use of more than 100 muscles.” How do we ever learn to say even this? In one of her most interesting chapters, Ms. Karpf tracks infant development from “the first cry” to the 12th month of life. The process by which babies learn to vocalize, muscle by muscle, vocable by vocable, takes on an epic quality in her account. One unexpected stage involves what she calls “learning through losing.” As she explains,

At birth, no matter what language community they’re born into, all babies perceive phonetics in the same way. As time passes, however, the range of sounds they hear diminishes until, at 6 months, they can only hear properly those that are salient in what will become their mother tongue. So while 6 and 8-month-old Japanese babies can hear ‘r’ and ‘l’ in the same way as English babies and adults, from around 10–12 months they no longer differentiate between the ‘r’ and ‘l’ because in Japanese these sounds belong to the same category.

Ms. Karpf is especially good on the differences between male and female voices, and the confusions — and injustices — these create. Because women have higher-pitched voices than men, they were long barred from radio; their voices were perceived as lacking credibility. It was only in 1933 that the BBC allowed one Mrs. Giles Borrett not to announce the news but to intone, “This is the ‘National’ program from London. The tea-time music today comes from the Hotel Metropole, London.” (NBC tried the same experiment in 1935 but soon canceled its first female announcer because of “her hoarse voice.”) But when she suggests, on the basis of random interviews, that men clammed up at home while their wives yelled their heads off — presumably in rebellion against their exclusion from public life — she seems to me to stretch the point a bit. To judge from the husbands’ clueless comments, the wives already had plenty to yell about.

By dwelling so resolutely on the actual physical voice and its emotional and social concomitants, Ms. Karpf illumines any number of small but irritating issues. Like everyone else, I hate the sound of my own voice on a recording, but why? This isn’t only because I hear my voice through the obstructions of my skull, from inside my head, and so don’t hear it as others do; rather, my own voice played back embarrasses me because it discloses my inmost self in a way that my words, so carefully chosen, do not. In hearing our voices as others hear them, we stand unwittingly exposed, and recordings make this clear.

For all its factual excellence, Ms. Karpf’s study remains pure reportage. A book on the voice, we might think, should have a voice itself and yet, her tone is studiously neutral from beginning to end. But as it happens, the Slovenian philosopher Mladen Dolar has now published “A Voice and Nothing More” (MIT Press, 214 pages, $19.95), a zany treatise on the voice that is short on fact but long on theory. The title comes from Plutarch. A man plucked a nightingale for his supper but on contemplating the scrawny pickings exclaimed, “You are a voice but nothing more!” Mr. Dolar’s treatise, heavily indebted to the musings of the French thinker Jacques Lacan, contains sentences like this: The reduction of the voice “is a non-signifying remainder resistant to the signifying operations, a leftover heterogeneous to structural logic, but precisely as such it seems to present a sort of counterweight to differentiality.” Mr. Dolar has a lot of voice. I’m just not sure what it’s saying. On the other hand, his book has one of the best blurbs I’ve read in a long time. According to Slavoj Z ÿ izÿek, “Mladen Dolar acts as if he is not an idiot and looks as if he is not an idiot, but this should not deceive you — he is NOT an idiot.”

I prefer Ms. Karpf’s more sober approach to Mr. Dolar’s madcap speculations. But I’m not sure either has captured the full mystery of the “vox humana.” Maybe Walt Whitman did it best. He was gabby but he listened. And he knew the stubborn power of articulated speech. As he put it, “My words itch at your ears till you understand them.”

eormsby@nysun.com