The Human Voice by Anne Karpf

When Anne Karpf told people she was writing a book about the human voice, their typical reaction was a prolonged silence. Then they would deny they had given it any thought. And then they would release a stream of observations about voices and their feelings towards them. "It's as if we both know and don't know about the voice," Karpf observes.

It's also as if we don't want to know. For many, perhaps most, our own voices are the ones we least want to hear. The conventional explanation is that we are lulled into a false sense of security by hearing our voices through the flattering insulation of our own bodies, and shocked when we hear them relayed through machines instead. Karpf prefers the Freudian explanation that when we hear our voices we are forced to hear things about ourselves to which we would rather be deaf. Both may be true: the voice is fundamental, intimate and difficult. There could hardly be a better subject for a book.

The pleasure Karpf takes in the voice is sustained throughout like a skylark's exaltation, carrying her through a heroic range of meticulously footnoted reading. She details the physiology of the vocal apparatus, ventures comparisons with other species, dwells upon the role of the voice in the relationships between mothers and babies; she charts the shifts in patterns of speech across time and social space, and comments pointedly upon vocal inequalities between the sexes.

Though her energy appears inexhaustible, her range is not limitless. She says almost nothing about singing, though that is where some of the voice's most remarkable talents are expressed; while her account of a scientific investigation of birdsong reveals misunderstanding (neurotransmitter receptors are not genes) and a more general confusion about what to make of elusive evolutionary hypotheses.

The omission of singing is an understandable decision, for the topic would likely have doubled the size of the book. Had it been included, however, it would surely have been impossible to overlook the significance of the collective voice. Karpf is marvellously attuned to individual voices and their interactions, but seems to hear little of the chants, the cheers and the ritual responses of crowd or congregation that do so much to make human societies what they are. The verse tells the story, but identity is the work of the chorus.

Although chanting may be hard to ignore at the moment, the roar of the political crowd and the sacred intonation of the church are easier to overlook in an age inaugurated by Franklin Roosevelt and his "fireside chats". The age of harangued masses was finally over in 1989 when the crowd answered the Romanian dictator Ceausescu back; political leadership now depends on the illusions of intimacy and personal contact.

Karpf provides fascinating discussions of the vocal styles of politicians - though even she is unable to fathom quite how Thatcher and Blair prospered despite the patently bogus concoctions they used to address the public. Analysis of Thatcher's voice revealed that over ten years "it had been artificially lowered by 60Hz, or about half the normal difference between a female and a male voice". Her freakishly acute Spitting Image imitator Steve Nallon would have been able to meet her half way.

Women's voices appear to have been moving in the same direction. The general rule appears to be that pitch follows power. When talk-show host Larry King interviewed guests of high status, such as Bill Clinton or Barbra Streisand, he shifted his pitch towards theirs. Conversely, lower-ranking guests shifted the pitches of their voices towards his.

Nor is the pressure only on pitch. "Today we're all professional voice-users," Karpf declares. The voice must be as appealing and as attentively polished as the smile. It must be ever ready to present, persuade and perform. Its talents will be developed by the need for it to be as flexible as any other element of labour.

Marek Kohn's 'A Reason for Everything' is published by Faber