| In the Chinese Mandarin system,tone and light stress are played a very important role in distinguishing meanings.However,according to the previous studies on cochlear implant recipients,it has been found that these implanters had widespread speech abnormality,which seriously influenced their language perception and output.This article intends to start with the perception and output of tone and stress,taking 4-5 year-old cochlear implanted children as the research object,and conducts in-depth analysis of their acquisition conditions and characteristics of tone and accent.This study can not only enrich the outcomes of the acquisition of speech for cochlear implant recipients,but also provide a theoretical reference for speech rehabilitation therapy in children with cochlear implants.The tone perception study includes two parts.The first study is a comparative experimental study on tone identification(quite,whisper)of the two groups of children.The second study is also a comparative experimental study,but on neutral tone discriminations(neutral tone-nonneutral tone;neutral tone-pitch modified neutral tone;neutral tone-duration modified neutral tone)of the two groups of children.12 prelingually deafened,native Mandarin-speaking cochlear implant children and 12 normal hearing children participated.The perception experiments are going to examine the tone and neutral tone recognition capabilities of cochlear implant children.The main results of the perception experiments are:(1)Whether it is the ability to identify the natural speech tone in a quiet environment or the ability to identify whispers tone with fundamental frequencies missing,children in the CI group are significantly weaker than those in the normal hearing group.In the face of whisper tone identification tasks,there are certain difficulties in both groups of subjects.However,the scores of the normal hearing group decreased more than that of the CI group,indicating that in the task of the perception of whisper tone,the normal hearing children's judgement was more likely to be affected by the fundamental frequency than the children of the CI group.(2)The two groups of children are easily confused on the identification of T2 and T3.The recognition rate of four tones from high to low are:T3>T4>T2>T1.Especially in the recognition rate of T3,the score of the normal hearing group(83.5%)was significantly higher than that of the CI group(61.7%).T3 may have the highest recognition rate because of its longest average time,which indicates that children in the normal hearing group are more sensitive to T3's duration than the children in CI group;or that some fine structures in time domain information can be used to assist their judgement.(3)Neutral tone discrimination experiments' results showed that,in the neutral tone discrimination,when the original tone is T1 and T2,CI children's recognition is better,while when the original tone is T3 and T4,especially T4,they have some difficulties to distinguish it.This may be due to the similarity of T4's neutral tone and non-neutral tone's post-word pitch contour,and the small difference in length,which makes it difficult to distinguish.(4)When only examining the influence of the fundamental frequency on their ability to distinguish between neutral tone and non-neutral tone,it was found that the modification of duration had little effect on the perception of neutral tone in normal hearing children,but their accuracy on T3 was significantly lower than that of other tones.It turns that the duration is a very important factor in the perception of T3 as the post-word of the neutral tone.Excluding the impact of duration,T4 for the post-word neutral tone perception of CI children still have a certain degree of difficulty,it can be inferred that children with CI is difficult to distinguish similar neutral tone and non-neutral tone only by virtue of the fundamental frequency.(5)When only examining the influence of the duration on their ability to distinguish between neutral tone and non-neutral tone,it was found that the CI group relied more on duration factors when discriminating neutral tone and non-neutral tone.However,normal hearing children and CI children have the most significant differences in the recognition when the post-word is T3.It shows that normal hearing children can rely on the difference in duration and fundamental frequency to perceive T3,and CI children are having flaws in the fundamental frequency perception,and there is a pitch inflection point in T3,which makes CI children particularly poor in perception of neutral tone and non-neutral tone in the post word T3.The production study also includes two parts.The first study is a comparative experimental study on tone production of the two groups of children.The second study is also a comparative experimental study but on focus sentences production of the two groups of children.The subjects are as same as those in the perception study.By comparing the tone production ability and focus sentence production ability of cochlear implanted children with those of normal hearing children,multiple related acoustic parameters such as fundamental frequency,duration,energy,and vocal sound were extracted through repetition.Through the analysis of variance of repeated measurement,we analyzed the difference in production ability between the two groups of children.The main findings are as follows:(1)From the fundamental frequency point of view,the two groups of children had significant difference only in the minimum fundamental frequency and the range of frequency.The minimum fundamental frequency of normal hearing children is significantly lower than the CI group,and the range of frequency is also significantly wider than the CI group.It indicating that the Cl children's tone production is characterized by a relatively flat fundamental frequency.(2)From the time point of view,in the two groups of children's voice,T3 has the longest duration of the sound,and T4 has the shortest duration of the sound.The duration of tone production in the normal hearing group was significantly shorter than that in the CI group.This shows that the sound output rate of children in the normal hearing group is faster than that of the CI group.(3)From the vocal point of view,the H1-A1,H1-A2,and HI-A3 in the normal hearing group were significantly larger than those in the CI group.This shows that when the impact of tone is not being considered,the output of the normal hearing group has a stronger gasification than the CI group.(4)The statistics of the fundamental frequency and energy of the focus sentences produced finds that the average value of the fundamental frequency,the maximum value of the fundamental frequency,the average value of the focus of the first word,the mean value of the final focus word,the energy mean value,the energy minimum value,and the energy maximum value of the narrow focus sentences are significantly greater than the wide focus sentences.The average fundamental frequency of children in the normal hearing group was significantly higher than that of the CI group.It indicated that,to some extent,the two groups of children could distinguish between wide focus sentences and narrow focus sentences.However,the interactive effects of focus types and groups are not significant in all fundamental frequency acoustic parameters and energy acoustic parameters,which means that the two groups of children aged 4-5 cannot well implemented focus at the end of the sentence.However,the children in the normal hearing group were still better than those in the CI group. |
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