We investigated the effects of aging on otoacoustic emission (OAE) using ILO88 and ILO92. Much works on OAE related to aging have been done, however most studies were carried out on subjects with impaired hearing mainly in the high-frequency range. In the present study, therefore, the effect of aging on OAE was investigated in normal subjects with hearing level within 20dB in the entire frequencies. Spontaneous otoacoustic emission (SOAE) measurements were obtained in 220 ears of women. Evoked otoacoustic emission (EOAE) and Distortion product otoacoustic emission (DPOAE) measurements were obtained in 80 SOAE free ears of both sexes. As for EOAE the frequency of 4-kHz filtered echo power and the total echo power were decreased with increasing age. In addition, the DP level at each frequency was decreased particulary in the high-frequency range. These findings suggest that EOAE and DPOAE reflect age-related changes in the acoustic system which were not detected by the pure tone hearing test. The significant difference in DP level in the mid-frequency range is presum-ably age-related change in the dynamic characteristics of the middle ear.
Speech reception of the hearing impaired who were using FM-wireless hearing aid systems was evaluated under the simulated noisy environments created in an anechoic room and under the practical noisy environments. The word intelligibility was investigated under two conditions of S/N=0dB and S/N=10dB in eleven subjects, who were the aged having sensorineural hearing impaiment with the mean hearing levels between 40dB and 70dB. The word intelligibility was increased by using the FM-wireless hearing aid system in the range of 5% to 55% or 15% to 70% compared with microphone inputs, in both testing conditions respectively. As the results, the trial use in practical environments showed good speech reception against the case of using their own hearing aids. Furthermore, a patient paging system composed of the FM-wireless hearing aid systems, was operated temporarily in a hospital lobby. Twenty six subjects with the mean hearing levels between 23dB and 100dB, who were waiting for medical examination and listening to CD-music through the FM-wireless hearing aid. When the name of patients was called through the wire-less equipment, it was found that the calling voice was perceived clearly by most subjects (81%) including severely hearing-impaired persons.
This study was carried out to compare the speech perception ability in patients using hearing aids with hearing levels of 90dB or more (31 patients) and cochlear implant (66 patients). The patients with hearing aids were divided into group 55dB (hearing levels with hearing aids -55dB, 7 patients), group 56-60dB (56-60dB, 8), group 61-65dB (61-65dB, 6), group 66-70dB (66-70dB, 6), and group 71dB (71dB or more, 4). The patients with cochlear implant were using the strategies of F0F1F2 (15 patients), MPEAK (30 patients) and SPEAK (21 patients). In the cochlear implant patients, means correct answer with auditory and visual in F0F1F2, MPEAK and SPEAK were 47.3%, 44.5% and 65.6% for monosyllables, 44.8%, 56.3% and 73.4% for words, 66.0%, 60.5% and 84.7% for sentences. In comparison with the results of patients with hearing aids, the speech perception for F0F1F2 and MPEAK were eqivalent to those of group 55-70dB, and those for SPEAK was better than those of group 55dB. In other words, the speech perception ability in conventional cochlear implant strategies-F0F1F2 and MPEAK-was corresponding to that of patients with hearing levels with hearing aids of 55-70dB, but that in new strategy-SPEAK-showed better results than those of 55dB or less.
Auditory perception and language development in nine male infants and children clinically suspected as having classical Pelizaeus-Merzbacher disease (PMD), were studied. PMD is an X-linked recessive, leukodystrophy in which myelination of the central nervous system fails to mature. The patients exhibited only wave I, or waves I and II when tested for auditory brain stem response, congenital pendular nystagmus, hypotonia, and tremors of head, trunk, and upper limbs in the early infantile period, and later developed progressive spasticity of the lower extremities. MRI demonstrated high-signal areas over the entire cerebral white matter on T2-weighted images, with inversion of the usual contrast in all cases. Three cases proved to have normal hearing, and six showed mild hearing impairment by pure tone or conditioned orientation reflex (COR) audiometry. The infants and children responded well to voices and sounds. Language development was evaluated in the patients, ranging from four years to twenty-two years of age, and it was noted that the comprehension of daily conversation was extremely good, while eight cases suffered from severe dysarthria, and one had ataxic speech. It is important to consider augmentative or alternative communication systems for such children, with neurogenic articulation problems.
In order to treat secretory otitis media (SOM), numerous types of ventilation tube have been used. The ventilation tubes were designed with the aim of long-term ventilation of the middle ear. However, there are few studies which investigate the effect of tube insertion on the transmission characteristics of the middle ear. In this study, three-dimensional finite-element method (FEM) model of a human middle ear is established by applying the FEM program developed by our group. Then, the effects of the materials and the site of placement of the ventilation tube on the transmission characteristics of the middle ear are analyzed. The following conclusions were obtained: (1) Low density materials such as silicone are suitable for ventilation tube. (2) When a light-weighed ventilation tube is used, the effect of the site of placement is small. When a relative heavy ventilation tube is used, the best site of placement is the antero-inferior quadrano.
The relationship between reaction time and training result in the frequency discrimination tasks for inexperienced elderly subjects was assessed. The correct rate of task is commonly used as the measure of learning. In this paper, a reaction time is also used as the measure of learning. Subjects were divided into two groups to examine the influence of instruction. One is “instruction group” who are instructed to make a quick response during the task, the other is “non-instruction group” who are not instructed to make a quick response. The results demonstrated that 1) a simple reaction time for detection of sound stimuli became stable in about 50 trials, then training was considered to be completed in both groups; 2) A reaction time in training session reached a plateau in about 160 trials of training, and it was suggested that a reaction time could be applied as one of completion criteria of the response action training in instruction group. 3) Frequency difference limen were tend to improve gradually. Thus we needed a criterion of which threshold should be adopted. We proposed that the first threshold after training completed in instruction group should be adopted. It was suggested that this idea could be applied as one of decision criteria of the threshold.
The purpose of this study is to ascertain the perception of music in cochlear implant users, 14 Nucleus system SPEAK users and 2 Clarion CIS users, with regard to the basic elements of music. Five tests were given: (1) Rhythm discrimination test, (2) Pitch discrimination Test, (3) Musical Instrument Timbre Identification Test, (4) Melody Identification Test, and (5) Acappella Singing Identification Test. Results showed that the most subjects were able to differentiate rhythm patterns with above 90% accuracy. The mean score was 51.8% for pitch, 25.8% for musical instrument timbre identification. The subjects identified the piano with greatest accuracy followed by xylopyone, and a person humming least accurately. The string instruments such as violin, guiter were identified with intermediate accuracy. For the identification of melodies, the mean score was 11.8%; however, with the same melody, when it was sung in acappella, the score improved to 71.4%. Those results indicated that the musical elements of pitch and timbre that requires the recognition of spectrum envelope were hard to be identified through the current cochlear implant system. However, the rhythm were well perceived due to the time intensity information. Neither the correlation was found between the speech perception ability and the musical perception, nor the difference in performance between the cochlear prosthesis was observed.
It is difficult to predict the prognosis of sudden hearing loss (SHL). Initial hearing level is commonly considered as a factor affecting the hearing outcome of SHL. The purpose of this study is to investigate the relationship between the initial residual hearing and the hearing outcome in profound SHL patients. We compared the hearing outcome in 20 patients of total deafness and that in 47 patients of nearly-total deafness (profound SHL without residual hearing at more than three frequencies). In nearly-total deafness patients, we compared the hearing outcome at each of 7 frequencies (125-8kHz) with and without initial residual hearing. We also compared the final hearing level (PTA: pure-tone average) of patients with and without initial residual hearing at each frequency. The outcome in the total deafness patients was poor and the average of mean final PTA was 78dB, although that of nearly-total deafness was varied and the average was 52dB. In 7 frequencies of nearly-total deafness patients, the difference in hearing outcome at the frequency with and without initial residual hearing was largest at 2kHz and smallest at 500Hz. The mean final PTA with initial residual hearing at 2kHz was 42dB, which was significantly smaller than 63dB, that without initial residual hearing. From these results, we concluded that the initial residual hearing at 2kHz might be a most important indicator predicting the prognosis of profound SHL.