It just so happens that motherese is in many ways ideally suited to stimulate young babies' sense of hearing. Its unhurried cadence is easier for babies to follow, since as we've seen, their nervous systems process auditory information at least twice as slowly as adults. Its louder, more direct style helps babies distinguish it from background sounds and overcomes the fact that their hearing is much less sensitive than adults'. Its simpler words and highly intonated structure—with wide swings in pitch and loudness that enhance the contrast between sequential syllables—make it much easier for babies to distinguish individual parts of speech. And finally, its high pitch corresponds to babies' most sensitive frequency range from the age of about three months onward. In many ways, then, motherese is an optimal auditory stimulus for babies, especially after the immediate newborn period, and it is particularly good for them as they begin to acquire the basics of their native language.

Mothers are not the only ones who speak in "motherese." Fathers, older siblings, and others also tend to talk to infants and small children in this special "baby talk" that my colleague found so objectionable. The same speech pattern has also been observed among infant caregivers across many different cultures. It's hard to say whether we use this speech purely instinctively or because we learned it when we ourselves were children. But whatever the reason parents begin speaking to their babies in motherese, the reason they continue to do so is because the babies respond better to it than to normal speech. For instance, four-month-old babies given a choice between listening to recordings of a strange woman speaking in motherese or in regular adult speech preferred the former, judging by the number of times they turned their heads to activate each recording. The earliest that babies have been shown to be capable of recognizing motherese is about five weeks of age. when they will suck more to hear recordings of their mothers speaking in a highly inflected voice than in a flat monotone.

The preference for motherese probably begins forming in the womb, where the intonation and pitch of the mother's voice are transmitted more faithfully than her specific speech sounds. The preference is then soundly reinforced after birth, since this mode of speech is inevitably accompanied by lots of affection and attention. Given the emotional reinforcement and the auditory features that make it so optimally stimulating to their hearing, motherese is one of the most potent forms of stimulation a young baby receives.

Babies prefer it when mothers speak in a highly- intonated cadence with slow emphasis on syllables highly repeated. This preference may begin in the womb, when such sounds are the only parts of the mother's speech to reach the fetus.

The tests show that babies\' preferences have nothing to do with the actual words mothers use. Babies choose motherese (or \"parentese\" or \"caretakerese\") even when the speaker is talking in a foreign language so infants can\'t understand the words, or when the words have been filtered out using computer techniques and only the pitch of the voice remains. Apparently they choose motherese not just because it\'s how their mother talks but because they like the way it sounds. Motherese is a sort of comfort language; it\'s like aural macaroni and cheese. Even grown-ups like it. Pat\'s graduate students discovered that listening to the lab tapes of motherese in a foreign language was a wonderful therapy for end-of-term stress. The mother\'s voice is an acoustic hook for the babies. It captures babies\' attention and focuses it on the person who is talking to them.

The elaborate techniques of computer voice analysis reveal exactly what it is we do when we talk to an infant. The pitch of our voice rises dramatically, sometimes by more than an octave; our intonation becomes very melodic and singsongy; and our speech slows down and has exaggerated, lengthened vowels.

Motherese is a universal language. People across all cul:ures do it when they talk to their infants, even though they usually aren\'t aware of doing it at all. When mothers listen to recordings of themselves producing motherese, the reaction is: That can\'t be me. I sound really stupid. Should I be doing that? But they do it intuitively, without conscious awareness.

Why do we do it? Do we produce motherese simply to get the babies\' attention? (It certainly does that.) Do we do it just to convey affection and comfort? Or does motherese have a more focused purpose? It turns out that motherese is more than just a sweet siren song we use to draw our babies to us. Motherese seems to actually help babies solve the Language problem.

Motherese sentences are shorter and simpler than sentences directed at adults. Moreover, grown-ups speaking to babies often repeat the same thing over and over with slight variations. (\"You are a pretty girl, aren\'t you? Aren\'t you a pretty girl? Pretty, pretty girl.\") These characteristics of motherese may help children to figure out the words and grammar of their language.

But the clearest evidence that motherese helps babies learn comes from studies of the sounds of motherese. Recent studies show that the well-formed, elongated consonants and vowels of motherese are particularly clear examples of speech sounds. Mothers and other caregivers are teachers as well as lovers. Completely unconsciously they produce sounds more clearly and pronounce them more accurately when they talk to babies than when they talk to other adults. When mothers say the word bead to an adult, it\'s produced in a fraction of a second and it\'s a bit sloppy. But when mothers say that same word to their infants, it becomes beeeeeed, a well-produced, clearly articulated word. This makes it easier for infants to map the sounds we use in language.

With its characteristic slow, repetitive enunciation of the words in culture\'s language, Motherese seems like an instinctual way a mother habituates their child to the sound categorizations of their language. This begs the question: if the Motherese imitates the sounds of another language, would that stave off the child\'s failure to distinguish foreign sounds later on?