The Japanese Industrial Standard for hearing aids, JIS C 5512, published in 1966, has been revised 4 times to reflect technical advances in hearing aids and also to meet the revisions of corresponding international standards. Major changes in the latest revision in 2015 were as follows: The acoustic coupler used to measure the output sound pressure level (SPL) of hearing aids was changed to a 2-cm³ coupler. The high-frequency average (average of gain or output SPL at 1000 Hz, 1600 Hz and 2500 Hz) was adopted as a representative of the performance of a hearing aid. The definitions of reference test gain and reference test setting of gain control were changed. Measurement of the performance characteristics of hearing aids with automatic gain control (AGC) was specified. Some of the above changes seemed to originate from the need to make the IEC standard more compatible with the ANSI standard. In addition, a standard specifying particular requirements for the basic safety and essential performance of hearing aids and hearing aid systems (JIS T 0601-2-66), and a standard specifying methods for characterizing signal processing in hearing aids with a speech-like signal (JIS C 5516) were newly published.
We developed a cartilage-conduction hearing aid for individuals who cannot use conventional hearing aids because of conditions such as atresia of the external auditory canal. Cartilage-conduction hearing is mediated by vibration of the aural cartilage, which is a third sound conduction pathway different from the well-known air and bone conduction pathways. Therefore, we investigated the results of daily use (one to three months) of a trial model of the new hearing aid, mainly in participants with atresia of the external ear canal. They then completed a questionnaire (including a visual analog scale [VAS] and a five-point scale) distributed to them to assess the hearing aid for hearing quality, amenity, and utility. For hearing quality, all participants gave high VAS scores (average 78/100 points). One of two participants who had the experience of using bone-anchored hearing aids (BAHAs) was satisfied with the hearing using the cartilage conduction hearing aid. On a five-point scale, all indicated that they could perceive the sound arrival direction because of the binaural effect. For amenity and utility, participants gave differing answers on both the VAS and five-point scales. However, most of them continued to use the cartilage-conduction hearing aid comfortably for a long period of time.
Numerous studies have shown that receiving cochlear implants in early childhood has positive effects on the language/learning ability in children with severe hearing loss. However, not many studies have been conducted to investigate the correlation between the hearing ability and language/learning ability in children with cochlear implants. The present study was conducted to examine the relationship between hearing ability and the results of evaluation by WISC-IV in children with cochlear implants. Assessment of the children's hearing ability was conducted by sound-field threshold measurements and the children's performance in speech recognition tests, speech discrimination tests and speech discrimination tests in noise. We found no correlation between the full-scale intelligent quotient (FSIQ) and the age at which the children received their cochlear implants. There were significant differences between the verbal comprehension index (VCI) and the perceptual reasoning index (PRI) in three children. Two of these 3 children had lower VCI values as compared to the PRI values; furthermore, their FSIQs were also low. The circumstances and hearing abilities of these two children accounted for their low scores. Our results demonstrated that the circumstances and hearing ability influence the language/learning ability in children with cochlear implants.
The association between the presence of a cleft palate and the incidence rate of otitis media with effusion (OME) was investigated in relation to the type of cleft palate and the age. Subjects were 60 children with cleft palate (29 boys, 31 girls) who came to were followed up at our hospital every year from 1 to 6 years of age. The presence of OME in each subject was regularly checked based on the condition of the ear drum. In addition, the association between the velopharyngeal closure function (VPC) on vocalization and the incidence rate of OME was investigated in the 48 children (21 boys, 27 girls) with a cleft palate who underwent testing of the VPC every year from 4 to 6 years of age. A high incidence rate of OME was found in children with a cleft palate, showing a decreasing trend with age. At the age of six years, the incidence rate was statistically significantly lower in children with an isolated cleft palate than that in the children with a cleft lip and palate. Based on these results, children with an isolated cleft palate were considered to become progressively less susceptible to OME as they grew in age, as compared to children with a cleft lip and palate. No association was found between the VPC on vocalization and the incidence rate of OME.
Hearing aids selectively amplify acoustic input to compensate for losses of hearing sensitivity. The purpose of this study was to investigate the changes in the auditory function caused by increase of the auditory input by with the use of hearing aids. This study was performed in 89 patients (168 ears) who presented with sensorineural hearing disturbance and underwent adaptation training for hearing aids at our hospital for three months. The baseline was defined by the maximum discrimination score before of the training. The maximum discrimination score under the unaided condition was measured at 3 and 6 months after the hearing aids were fitted. As compared to the baseline score, a greater than 10% improvement in the maximum discrimination score was observed in 34.5% of the subjects at 3 months and in 37.3% of the subjects at 6 months after the fitting of the hearing aids. Statistically significant relationships were observed between the percent improvement in the discrimination score and the baseline score, age and pure-tone averages. A negative correlation was only observed between the percent improvement in the discrimination score and the baseline score. The improvement in unaided speech discrimination, which is strongly related to the auditory acclimatization effect, suggested that correct use of hearing aids can induce auditory plasticity.