Auditory evoked potentials are useful for evaluation of auditory cognition required for language acquisition. Peaks of recorded waves represent synchronized spikes in clusters of neurons at each component along peripheral and central auditory pathways. Auditory brainstem response (ABR), which is available the most easily, is applied even for newborns, and latencies of peaks get shortened as myelination progresses. Comparison between responses of multiple stimuli is a basic strategy to observe the process of auditory cognition of language in event related potential (ERP). Mismatch negativity is an example of such a method, and it has proved that infants acquire abilities to discriminate fundamental properties of their mother tongue, such as specific duration of each phoneme and various kinds of prosody. Negative deflection around 400 milliseconds (N400) has revealed that 18-month-old children discriminate meanings of acoustically presented words. Detection of syntactic violation and understanding of sentences in 3-year-olds have been demonstrated on ERPs at 400-800 ms latency.
Auditory agnosia is the result of damage to the bilateral primary auditory cortex or auditory radiation. Patients with auditory agnosia cannot differentiate verbal or nonverbal (such as enviromental or musical) sounds, but their internal language is intact. Auditory agnosia in children is a very rare condition and is often misunderstood or overlooked. In this manuscript, the author describes case reports of auditory agnosia caused by herpes encephalitis, adrenoleukodystrophy, and Landau-Kleffner syndrome, and focuses on the importance of early diagnosis of such conditions. The author also introduces similar but different conditions such as developmental language disorders and auditory neuropathy/auditory nerve diseases.
For the purpose of developing a Japanese checklist for differential diagnosis between stuttering and cluttering, I translated Daly's checklist (reported in 1993) into Japanese and distributed it to teachers who work in special classes for speech-language disorders in elementary schools, in order to assess students who stutter. The results showed that, out of 208 students, 33 students were screened as clutterers. In addition, factor analysis was applied to these results, and I found three factors: language disorders and poor motor speech control, attention deficit/hyperactivity, and rapid speech rate. Moreover, in comparisons between the cluttering group and stuttering group for all items on the checklist, out of 33 items the clutterers indicated a higher score significantly in 31 items. These results show that this Japanese checklist for possible cluttering is appropriate for screening cluttering. In the future, I intend to examine the validity and clinical effectiveness of this Japanese cluttering checklist in a series of surveys on clinical intervention for people diagnosed by this checklist.
This study examined the effect of entry age of intervention in hearing-impaired children with cochlear implants (CI children, n=18), together with hearing-impaired children with hearing aids (HA children, n=26). All these children had a hearing loss of 90dB or over and had received the same early auditory-verbal/oral intervention program. We assessed their language abilities using the WPPSI Intelligence Test at 6 years of age. Statistic analysis showed that significantly higher Verbal IQ scores (age-appropriate scores) were noted in CI children of entry under 12 months of age and cochlear implantation at 2 years of age than in children of entry at 2 years of age and cochlear implantation at older than 3 years. Compared with a small percentage (14.2%) of language delay (VIQ score below 80) in CI children of entry at 2 years of age, there was a higher percentage (70.0%) of language delay in children with hearing aids of entry at 2 years of age. These results demonstrated a significant effect of entry age of intervention and the significant benefits of cochlear implantation in children with hearing loss of 90dB or over.
We investigated the current state of communication of 111 persons with hearing impairment by conducting a questionnaire survey. The subjects were 15 to 46 years old and had been educated by the aural-oral method. Their hearing loss in childhood was under 90 dBHL. Their current mean of better ear hearing loss was 80.1 dBHL, SD=19.9. By examining their use of communication methods according to communication partner, speech perception in a person-to-person conversation under both silent and noisy conditions, their use of a compensator of communication in a business meeting and school lecture, communication strategies, and use of communication methods in tele-communication, the study yielded the following results. 1) When speaking with others, the subjects made use of their voice to both hearing persons and persons with hearing impairment. 2) The subjects whose better ear hearing loss was over 80 dBHL had difficulties of speech perception under specific conditions such as noisy locations and group communication. These results suggest that individuals who were educated by the aural-oral method and whose better ear hearing loss was under 90 dBHL in childhood make use primarily of their voice after graduating junior high school.
The Japanese Articulation Test (second edition) enables us to analyze several aspects of phonological processes such as place, manner, and voicing/non-voicing of consonants via free descriptions by speech therapists in the "Summary of Phonetic Viewpoint" section. However, it is difficult to conduct detailed analyses of phonological processes without certain knowledge of phonological disorders and processes. In this paper, we introduce a tentative version of the Phonological Process Analysis Tool which can be adjunctively administered with the Japanese Articulation Test (second edition). This tool enables even novice speech therapists to correctly analyze phonological processes by checking against the list on the phonological processes record form. Fifteen phonological processes were chosen as the target phoneme processes for this tool. They were first divided into two broad categories, which were the whole-word and the segment change processes. The reduction process was set as the sub-category of the whole-word process; and the voicing, place and manner, and nasalization processes were set as the sub-categories of the segment change process. At the present stage, only the percentage of the phonological process is calculated via the Phonological Process Analysis Tool because it is not yet standardized. As the next step, the relations among age and types and number of phoneme processes should be clarified via data collection with the aim of arriving at standardization in the future.
Nine deaf children aged 5-14 years who complained of hyperacusis after receiving cochlear implantation were selected from approximately 80 implanted children treated at our institutions. Characteristics of hyperacusis in these children were compared with those of ten non-implanted children aged 4-12 years, including five normal hearing children and five children with sensorineural hearing loss who complained of hyperacusis. Six of the nine implanted children as well as six of the ten non-implanted children were associated with autism spectrum disorder or Asperger's syndrome. Acoustic stimuli causing hyperacusis in these children were noise produced by a vacuum cleaner, hair dryer or flush toilet, sudden noises produced during construction work, big sounds produced by crowds of people, etc. No differences concerning the types of these causal stimuli were found between the implanted children and the non-implanted children. Although the majority of the implanted children gradually overcame their hyperacusis, one case with autism spectrum disorder and severe mental retardation who had received cochlear implantation at the age of five years began to refuse to use his cochlear implant when he reached 10 years of age. In this particular case, rejection of the cochlear implant was thought to be due to hyperacusis. These findings suggest that hyperacusis in the majority of our implanted children may be attributed to autism spectrum disorder, and in the severest case hyperacusis can cause a child to reject the use of a cochlear implant.
Although the verbal IQs of children with high-functioning pervasive developmental disorders (HFPDD) are normal, discrepancies exist between observed test values and actual situations. Using the Illinois Test of Psycholinguistic Abilities (ITPA), this study investigated trends in 101 children with HFPDD in order to clarify communication and language problems in children with HFPDD. The results showed that while there was no significant delay found in all-test scaled scores, scores were lower in the categories of “Auditory Association,” “Verbal Expression” and “Grammatic Closure.” These differences reflect communication and language problems in children with HFPDD, and suggest problems of processing in the hearing/vocalization system, understanding contexts and performance in semantic categories.