Long before they can actually speak, babies pay special attention to the speech they he

Long before they can actually speak, babies pay special attention to the speech they

hear around them. Within the first month of their lives, babies' responses to the sound of

the human voice will be different from their responses to other sorts of auditory stimuli.

They will stop crying when they hear a person talking, but not if they hear a bell or the

(5) sound of a rattle. At first, the sounds that an infant notices might be only those words that

receive the heaviest emphasis and that often occur at the ends of utterances. By the time

they are six or seven weeks old, babies can detect the difference between syllables

pronounced with rising and falling inflections. Very soon, these differences in adult stress

and intonation can influence babies' emotional states and behavior. Long before they

(10) develop actual language comprehension, babies can sense when an adult is playful or

angry, attempting to initiate or terminate new behavior, and so on, merely on the basis of

cues such as the rate, volume, and melody of adult speech.

Adults make it as easy as they can for babies to pick up a language by exaggerating

such cues. One researcher observed babies and their mothers in six diverse cultures and

(15) found that, in all six languages, the mothers used simplified syntax, short utterances and

nonsense sounds, and transformed certain sounds into baby talk. Other investigators have

noted that when mothers talk to babies who are only a few months old, they exaggerate

the pitch, loudness, and intensity of their words. They also exaggerate their facial

expressions, hold vowels longer, and emphasize certain words.

(20) More significant for language development than their response to general intonation is

observation that tiny babies can make relatively fine distinctions between speech sounds.

other words, babies enter the world with the ability to make precisely those perceptual

discriminations that are necessary if they are to acquire aural language.

Babies obviously derive pleasure from sound input, too: even as young as nine months

(25) they will listen to songs or stories, although the words themselves are beyond their

understanding. For babies, language is a sensory-motor delight rather than the route to

prosaic meaning that it often is for adults.

What does the passage mainly discuss？

A．How babies differentiate between the sound of the human voice and other sounds

B．The differences between a baby's and an adult's ability to comprehend language

C．How babies perceive and respond to the human voice in their earliest stages of language development

D．The response of babies to sounds other than the human voice