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  • Sound is at the beginning of language learning. Children have to learn to

  • distinguish different sounds and to segment the speech stream they are

  • exposed to into unitseventually meaningful unitsin order to acquire

  • words and sentences. Here is one reason that speech segmentation is challenging:

  • When you read, there are spaces between the words. No such spaces occur between

  • spoken words. So, if an infant hears the sound sequencethisisacup,” it has to

  • learn to segment this stream into the distinct unitsthis”, “is”, “a”, and

  • cup.” Once the child is able to extract the sequencecupfrom the speech

  • stream it has to assign a meaning to this word. Furthermore, the child has to

  • be able to distinguish the sequencecupfromcubin order to learn that

  • these are two distinct words with different meanings. Finally, the child

  • has to learn to produce these words. The acquisition of native language phonology

  • begins in the womb and isn’t completely adult-like until the teenage years.

  • Perceptual abilities usually precede production and thus aid the development

  • of speech production. Prelinguistic development

  • = Perception = Children don’t utter their first words

  • until they are about 1 year old, but already at birth they can tell some

  • utterances in their native language from utterances in languages with different

  • prosodic features. 1 month

  • = Categorical perception = Infants as young as 1 month perceive

  • some speech sounds as speech categories. For example, the sounds and differ in

  • the amount of breathiness that follows the opening of the lips. Using a

  • computer generated continuum in breathiness between and , Eimas et al.

  • showed that English-learning infants paid more attention to differences near

  • the boundary between and than to equal-sized differences within the

  • -category or within the -category. Their measure, monitoring infant sucking-rate,

  • became a major experimental method for studying infant speech perception.

  • Infants up to 10–12 months can distinguish not only native sounds but

  • also nonnative contrasts. Older children and adults lose the ability to

  • discriminate some nonnative contrasts. Thus, it seems that exposure to one’s

  • native language causes the perceptual system to be restructured. The

  • restructuring reflects the system of contrasts in the native language.

  • 4 months At four months infants still prefer

  • infant-directed speech to adult-directed speech. Whereas 1-month-olds only

  • exhibit this preference if the full speech signal is played to them,

  • 4-month-old infants prefer infant-directed speech even when just

  • the pitch contours are played. This shows that between 1 and 4 months of

  • age, infants improve in tracking the suprasegmental information in the speech

  • directed at them. By 4 months, finally, infants have learned which features they

  • have to pay attention to at the suprasegmental level.

  • 5 months Babies prefer to hear their own name to

  • similar sounding words. It is possible that they have associated the meaning

  • mewith their name, although it is also possible that they simply recognize

  • the form because of its high frequency. 6 months

  • With increasing exposure to the ambient language, infants learn not to pay

  • attention to sound distinctions that are not meaningful in their native language,

  • e.g., two acoustically different versions of the vowel that simply

  • differ because of inter-speaker variability. By 6 months of age infants

  • have learned to treat acoustically different sounds that are

  • representations of the same sound category, such as an spoken by a male

  • versus a female speaker, as members of the same phonological category .

  • = Statistical learning = Infants are able to extract meaningful

  • distinctions in the language they are exposed to from statistical properties

  • of that language. For example, if English-learning infants are exposed to

  • a prevoiced to voiceless unaspirated continuum with the majority of the

  • tokens occurring near the endpoints of the continuum, i.e., showing extreme

  • prevoicing versus long voice onset times they are better at discriminating these

  • sounds than infants who are exposed primarily to tokens from the center of

  • the continuum. These results show that at the age of 6

  • months infants are sensitive to how often certain sounds occur in the

  • language they are exposed to and they can learn which cues are important to

  • pay attention to from these differences in frequency of occurrence. In natural

  • language exposure this means typical sounds in a language occur often and

  • infants can learn them from mere exposure to them in the speech they

  • hear. All of this occurs before infants are aware of the meaning of any of the

  • words they are exposed to, and therefore the phenomenon of statistical learning

  • has been used to argue for the fact that infants can learn sound contrasts

  • without meaning being attached to them. At 6 months, infants are also able to

  • make use of prosodic features of the ambient language to break the speech

  • stream they are exposed to into meaningful units, e.g., they are better

  • able to distinguish sounds that occur in stressed vs. unstressed syllables. This

  • means that at 6 months infants have some knowledge of the stress patterns in the

  • speech they are exposed and they have learned that these patterns are

  • meaningful. 7 months

  • At 7.5 months English-learning infants have been shown to be able to segment

  • words from speech that show a strong-weak stress pattern, which is the

  • most common stress pattern in the English language, but they were not able

  • to segment out words that follow a weak-strong pattern. In the sequence

  • guitar isthese infants thus heardtarisas the word-unit because it

  • follows a strong-weak pattern. The process that allows infants to use

  • prosodic cues in speech input to learn about language structure has been termed

  • prosodic bootstrapping”. 8 months

  • While children generally don’t understand the meaning of most single

  • words yet, they understand the meaning of certain phrases they hear a lot, such

  • asStop it,” orCome here.” 9 months

  • Infants can distinguish native from nonnative language input using phonetic

  • and phonotactic patterns alone, i.e., without the help of prosodic cues. They

  • seem to have learned their native language’s phonotactics, i.e., which

  • combinations of sounds are possible in the language.

  • 10-12 months Infants now can no longer discriminate

  • most nonnative sound contrasts that fall within the same sound category in their

  • native language. Their perceptual system has been tuned to the contrasts relevant

  • in their native language. As for word comprehension, Fenson et al. tested

  • 10-11-month-old children’s comprehension vocabulary size and found a range from

  • 11 words to 154 words. At this age, children normally have not yet begun to

  • speak and thus have no production vocabulary. So clearly, comprehension

  • vocabulary develops before production vocabulary.

  • = Production = Stages of pre-speech vocal development

  • Even though children do not produce their first words until they are

  • approximately 12 months old, the ability to produce speech sounds starts to

  • develop at a much younger age. Stark distinguishes five stages of early

  • speech development: = 0-6 weeks: Reflexive vocalizations =

  • These earliest vocalizations include crying and vegetative sounds such as

  • breathing, sucking or sneezing. For these vegetative sounds, infantsvocal

  • cords vibrate and air passes through their vocal apparatus, thus

  • familiarizing infants with processes involved in later speech production.

  • = 6-16 weeks: Cooing and laughter = Infants produce cooing sounds when they

  • are content. Cooing is often triggered by social interaction with caregivers

  • and resembles the production of vowels. = 16-30 weeks: Vocal play =

  • Infants produce a variety of vowel- and consonant-like sounds that they combine

  • into increasingly longer sequences. The production of vowel sounds precedes the

  • production of consonants, with the first back consonants being produced around

  • 2–3 months, and front consonants starting to appear around 6 months of

  • age. As for pitch contours in early infant utterances, infants between 3 and

  • 9 months of age produce primarily flat, falling and rising-falling contours.

  • Rising pitch contours would require the infants to raise subglottal pressure

  • during the vocalization or to increase vocal fold length or tension at the end

  • of the vocalization, or both. At 3 to 9 months infants don’t seem to be able to

  • control these movements yet. = 6-10 months: Reduplicated babbling =

  • Reduplicated babbling contains consonant-vowel syllables that are

  • repeated in reduplicated series of the same consonant and vowel. At this stage,

  • infantsproductions resemble speech much more closely in timing and vocal

  • behaviors than at earlier stages. Starting around 6 months babies also

  • show an influence of the ambient language in their babbling, i.e.,

  • babiesbabbling sounds different depending on which languages they hear.

  • For example, French learning 9-10 month-olds have been found to produce a

  • bigger proportion of prevoiced stops in their babbling than English learning

  • infants of the same age. This phenomenon of babbling being influenced by the

  • language being acquired has been called babbling drift.

  • = 10-14 months: Nonreduplicated babbling Infants now combine different vowels and

  • consonants into syllable strings. At this stage, infants also produce various

  • stress and intonation patterns. During this transitional period from babbling

  • to the first word children also produceprotowords”, i.e., invented words that

  • are used consistently to express specific meanings, but that are not real

  • words in the children’s target language. Around 12–14 months of age children

  • produce their first word. Infants close to one year of age are able to produce

  • rising pitch contours in addition to flat, falling, and rising-falling pitch

  • contours. Development once speech sets in

  • At the age of 1, children only just begin to speak, and their utterances are

  • not adult-like yet at all. Children’s perceptual abilities are still

  • developing, too. In fact, both production and perception abilities

  • continue to develop well into the school years, with the perception of some

  • prosodic features not being fully developed until about 12 years of age.

  • = Perception = 14 months

  • Children are able to distinguish newly learnedwordsassociated with objects

  • if they are not similar sounding, such aslifandneem’. They cannot

  • distinguish similar sounding newly learned words such asbihanddih’,

  • however. So, while children at this age are able to distinguish monosyllabic

  • minimal pairs at a purely phonological level, if the discrimination task is

  • paired with word meaning, the additional cognitive load required by learning the

  • word meanings leaves them unable to spend the extra effort on distinguishing

  • the similar phonology. 16 months

  • Children’s comprehension vocabulary size ranges from about 92 to 321 words. The

  • production vocabulary size at this age is typically around 50 words. This shows

  • that comprehension vocabulary grows faster than production vocabulary.

  • 18-20 months At 18–20 months infants can distinguish

  • newly learnedwords’, even if they are phonologically similar, e.g. ‘bihand

  • dih’. While infants are able to distinguish syllables like these already

  • soon after birth, only now are they able to distinguish them if they are

  • presented to them as meaningful words rather than just a sequence of sounds.

  • Children are also able to detect mispronunciations such asvabyfor

  • baby’. Recognition has been found to be poorer for mispronounced than for

  • correctly pronounced words. This suggests that infantsrepresentations

  • of familiar words are phonetically very precise. This result has also been taken

  • to suggest that infants move from a word-based to a segment-based

  • phonological system around 18 months of age.

  • = Fast-mapping = Of course, the reason why children need

  • to learn the sound distinctions of their language is because then they also have

  • to learn the meaning associated with those different sounds. Young children

  • have a remarkable ability to learn meanings for the words they extract from

  • the speech they are exposed to, i.e., to map meaning onto the sounds. Often

  • children already associate a meaning with a new word after only one exposure.

  • This is referred to asfast mapping”. At 20 months of age, when presented with

  • three familiar objects and one unfamiliar object, children are able to

  • conclude that in the requestCan I have the zib,” zib must refer to the

  • unfamiliar object, i.e., the egg piercer, even if they have never heard

  • that pseudoword before. Children as young as 15 months can complete this

  • task successfully if the experiment is conducted with fewer objects. This task

  • shows that children aged 15 to 20 months can assign meaning to a new word after

  • only a single exposure. Fast mapping is a necessary ability for children to

  • acquire the number of words they have to learn during the first few years of

  • life: Children acquire an average of nine words per day between 18 months and

  • 6 years of age. 2–6 years

  • At 2 years, infants show first signs of phonological awareness, i.e., they are

  • interested in word play, rhyming, and alliterations. Phonological awareness

  • does continue to develop until the first years of school. For example, only about

  • half of the 4- and 5-year olds tested by Liberman et al. were able to tap out the

  • number of syllables in multisyllabic words, but 90% of the 6-year-olds were

  • able to do so. Most 3-4-year olds are able to break simple

  • consonant-vowel-consonant syllables up into their constituents. The onset of a

  • syllable consists of all the consonants preceding the syllable’s vowel, and the

  • rime is made up of the vowel and all following consonants. For example, the

  • onset in the worddogis and the rime is . Children at 3–4 years of age were

  • able to tell that the nonwords and would be liked by a puppet whose

  • favorite sound is . 4-year olds are less successful at this task if the onset of

  • the syllable contains a consonant cluster, such as or . Liberman et al.

  • found that no 4-year-olds and only 17% of 5-year-olds were able to tap out the

  • number of phonemes in a word. 70% of 6-year-olds were able to do so. This

  • might mean that children are aware of syllables as units of speech early on,

  • while they don’t show awareness of individual phonemes until school age.

  • Another explanation is that individual sounds do not easily translate into

  • beats, which makes clapping individual phonemes a much more difficult task than

  • clapping syllables. One reason why phoneme awareness gets much better once

  • children start school is because learning to read provides a visual aid

  • as how to break up words into their smaller constituents.

  • 12 years Although children perceive rhythmic

  • patterns in their native language at 7–8 months, they are not able to reliably

  • distinguish compound words and phrases that differ only in stress placement,

  • such asHOT dogvs. ‘hot DOGuntil around 12 years of age. Children in a

  • study by Vogel and Raimy were asked to show which of two pictures was being

  • named. Children younger than 12 years generally preferred the compound reading

  • to the phrasal reading. The authors concluded from this that children start

  • out with a lexical bias, i.e., they prefer to interpret phrases like these

  • as single words, and the ability to override this bias develops until late

  • in childhood. = Production =

  • 12-14 months Infants usually produce their first word

  • around 12 –14 months of age. First words are simple in structure and contain the

  • same sounds that were used in late babbling. The lexical items they produce

  • are probably stored as whole words rather than as individual segments that

  • get put together online when uttering them. This is suggested by the fact that

  • infants at this age may produce the same sounds differently in different words.

  • 16 months Children’s production vocabulary size at

  • this age is typically around 50 words, although there is great variation in

  • vocabulary size among children in the same age group, with a range between 0

  • and 160 words for the majority of children.

  • 18 months Children’s productions become more

  • consistent around the age of 18 months. When their words differ from adult

  • forms, these differences are more systematic than before. These systematic

  • transformations are referred to asphonological processes”, and often

  • resemble processes that are typically common in the adult phonologies of the

  • world’s languages. Some common phonological processes are listed below.

  • = Whole word processes = - Weak syllable deletion: omission of an

  • unstressed syllable in the target word, e.g., [nænæ] forbanana

  • - Final consonant deletion: omission of the final consonant in the target word,

  • e.g., [pikʌ] forbecause’ - Reduplication: production of two

  • identical syllables based on one of the target word syllables, e.g., [baba] for

  • bottle’ - Consonant harmony: a target word

  • consonant takes on features of another target word consonant, e.g., [ɡʌk] for

  • duck’ - Consonant cluster reduction: omission

  • of a consonant in a target word cluster, e.g., [kæk] forcracker

  • = Segment substitution processes = - Velar fronting: a velar is replaced by

  • a coronal sound, e.g., [ti] forkey’ - Stopping: a fricative is replaced by a

  • stop, e.g., [ti] forsea’ - Gliding: a liquid is replaced by a

  • glide, e.g., [wæbɪt] forrabbit’ 2 years

  • The size of the production vocabulary ranges from about 50 to 550 words at the

  • age of 2 years. Influences on the rate of word learning, and thus on the wide

  • range of vocabulary sizes of children of the same age, include the amount of

  • speech children are exposed to by their caregivers as well as differences in how

  • rich the vocabulary in the speech a child hears is. Children also seem to

  • build up their vocabulary faster if the speech they hear is related to their

  • focus of attention more often. This would be the case if a caregiver talks

  • about a ball the child is currently looking at.

  • 4 years A study by Gathercole and Baddeley

  • showed the importance of sound for early word meaning. They tested the

  • phonological memory of 4- and 5-year-old children, i.e., how well these children

  • were able to remember a sequence of unfamiliar sounds. They found that

  • children with better phonological memory also had larger vocabularies at both

  • ages. Moreover, phonological memory at age 4 predicted the children’s

  • vocabulary at age 5, even with earlier vocabulary and nonverbal intelligence

  • factored out. 7 years

  • Children produce mostly adult-like segments. Their ability to produce

  • complex sound sequences and multisyllabic words continues to improve

  • throughout middle childhood. Biological foundations of infants

  • speech development The developmental changes in infants

  • vocalizations over the first year of life are influenced by physical

  • developments during that time. Physical growth of the vocal tract, brain

  • development, and development of neurological structures responsible for

  • vocalization are factors for the development of infantsvocal

  • productions. = Infantsvocal tract =

  • Infants vocal tracts are smaller, and initially also shaped differently from

  • adultsvocal tracts. The infant’s tongue fills the entire mouth, thus

  • reducing the range of movement. As the facial skeleton grows, the range for

  • movement increases, which probably contributes to the increased variety of

  • sounds infants start to produce. Development of muscles and sensory

  • receptors also gives infants more control over sound production. The

  • limited movement possible by the infant jaw and mouth might be responsible for

  • the typical consonant-vowel alternation in babbling and it has even been

  • suggested that the predominance of CV syllables in the languages of the world

  • might evolutionarily have been caused by this limited range of movements of the

  • human vocal organs. The differences between the vocal tract

  • of infants and adults can be seen in figure 3 and figure 4 below.

  • = The nervous system = Crying and vegetative sounds are

  • controlled by the brain stem, which matures earlier than the cortex.

  • Neurological development of higher brain structures coincides with certain

  • developments in infantsvocalizations. For example, the onset of cooing at 6 to

  • 8 weeks happens as some areas of the limbic system begin to function. The

  • limbic system is known to be involved in the expression of emotion, and cooing in

  • infants is associated with a feeling of contentedness. Further development of

  • the limbic system might be responsible for the onset of laughter around 16

  • weeks of age. The motor cortex, finally, which develops later than the

  • abovementioned structures may be necessary for canonical babbling, which

  • start around 6 to 9 months of age. References

Sound is at the beginning of language learning. Children have to learn to

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