Acoustic Expression Research On Infants

Acoustic expression means producing sound with respect to different needs. Due to the fact that infants cannot speak yet, they have special features when it comes to expressing themselves.The object of this research is two-year-old infants. The researcher has recorded the speech samples of the infants since they were born to two years old. The samples include crying sound, laughter and speech sounds. The parameters extracted involve pitch, power, period of crying sounds and laughter as well as pitch, formants and spectrum of speech sounds. Hence, the researcher summarizes acoustic expression changes of infants in physiology and cognition. After segmentation, the samples of crying sounds, laughter and speech sounds reach167,96and376respectively, and the results are as follows.Emotionally:at the beginning, the crying sound includes three kinds, namely crying out loudly, crying in a lower voice and self-control crying. With time goes by, the infants mostly cry in a lower voice which tends to be the preparation for pronunciation as this kind of cry is always followed by clear speech. When it comes to laughter, the infants always laugh involuntarily in the beginning while turn to be amused to laugh with growth. The former kind of laugh disappears slowly.Speech:In vowel acquisition, infants learn speech in the sequence of/a//e//o//i//u//u/. And they learn simple monophthongs before diphthongs and triphthongs, often begins with/a/. Their pronunciation becomes more accurate with growth. As for consonant, it focused on bilabial consonant, apical consonant and radical consonant.Physiology:The speech of infants is restrained by vocal cords, bilabial and tongue. The development of vocal cords makes pitch change. The development of bilabial makes infants be able to pronounce bilabial consonant firstly. The movement of tongue decides the acquisition sequence of vowels and makes infants be able to pronounce apical consonant and radical consonant before they are two years old.Cognition:Infants begin to show cognition change after they are three months old. They can understand parents’ orders after nine months old. Later on, they can understand nouns that refer to specific objects and then understand action orders. About two years old, they can learn words that have distinguish meaning.