سناء احمد
30-10-2010, 06:49 PM
Infant speech perceptionInfants begin the process of language acquisition by being able to detect very
small differences between speech sounds. They are able to discriminate all possible speech contrasts (
phonemes
). Gradually, as they are exposed to their native language, their perceptio
n becomes language-specific, i.e. they learn how to ignore the differences within phonemic categories of the language (differences that may well be contrastive in other languages – for example, English distinguishes two voicing categories of stop consonants, whereas Thai has three categories; infants must learn which differences are distinctive in their native language uses, and which are not).
As infants learn how to sort incoming speech sounds into categories, ignoring irrelevant differences and reinforcing the contrastive ones,
their perception becomes
categorical.
Infants learn to contrast different vowel phonemes of their native language by approximately 6 months of age.
The native consonantal contrasts are acquired by 11 or 12 months of age.
[17] Some researchers have proposed that infants may be able to learn the sound categories of their native language through
passive listening, using a process called statistical learning. Others even claim that certain sound categories are innate, that is, they are genetically-specified (see discussion about innate vs. acquired categorical distinctiveness).
If day-old babies are presented with their mother's voice speaking normally, abnormally (in monotone), and a stranger's voice, they react only to their mother's voice speaking normally. When a human and a non-human sound is played, babies turn their head only to the source of human sound. It has been suggested that auditory learning begins already in the pre-natal period.[18]
How do researchers know if infants can distinguish between speech sounds? One of the techniques used to examine how infants perceive speech, besides the head-turn procedure mentioned above, is measuring their sucking rate. In such an experiment, a baby is sucking a special nipple while presented with sounds. First, the baby's normal sucking rate is established. Then a stimulus is played repeatedly. When the baby hears the stimulus for the first time the sucking rate increases but as the baby becomes habituated to the stimulation the sucking rate decreases and levels off. Then,
a new stimulus is played to the baby. If the baby perceives the newly introduced stimulus as different from the background stimulus the sucking rate will show an increase.[18] The sucking-rate and the head-turn method are some of the more traditional, behavioral methods for studying speech perception. Among the new methods (see Research methods below) that help us to study speech perception, NIRS is widely used in infants.[17]
small differences between speech sounds. They are able to discriminate all possible speech contrasts (
phonemes
). Gradually, as they are exposed to their native language, their perceptio
n becomes language-specific, i.e. they learn how to ignore the differences within phonemic categories of the language (differences that may well be contrastive in other languages – for example, English distinguishes two voicing categories of stop consonants, whereas Thai has three categories; infants must learn which differences are distinctive in their native language uses, and which are not).
As infants learn how to sort incoming speech sounds into categories, ignoring irrelevant differences and reinforcing the contrastive ones,
their perception becomes
categorical.
Infants learn to contrast different vowel phonemes of their native language by approximately 6 months of age.
The native consonantal contrasts are acquired by 11 or 12 months of age.
[17] Some researchers have proposed that infants may be able to learn the sound categories of their native language through
passive listening, using a process called statistical learning. Others even claim that certain sound categories are innate, that is, they are genetically-specified (see discussion about innate vs. acquired categorical distinctiveness).
If day-old babies are presented with their mother's voice speaking normally, abnormally (in monotone), and a stranger's voice, they react only to their mother's voice speaking normally. When a human and a non-human sound is played, babies turn their head only to the source of human sound. It has been suggested that auditory learning begins already in the pre-natal period.[18]
How do researchers know if infants can distinguish between speech sounds? One of the techniques used to examine how infants perceive speech, besides the head-turn procedure mentioned above, is measuring their sucking rate. In such an experiment, a baby is sucking a special nipple while presented with sounds. First, the baby's normal sucking rate is established. Then a stimulus is played repeatedly. When the baby hears the stimulus for the first time the sucking rate increases but as the baby becomes habituated to the stimulation the sucking rate decreases and levels off. Then,
a new stimulus is played to the baby. If the baby perceives the newly introduced stimulus as different from the background stimulus the sucking rate will show an increase.[18] The sucking-rate and the head-turn method are some of the more traditional, behavioral methods for studying speech perception. Among the new methods (see Research methods below) that help us to study speech perception, NIRS is widely used in infants.[17]