There has been a phenomenal increase in the number of children with unilateral hearing loss (ULHL) detected by early newborn hearing screening. However, the prevalence of ULHL remains unknown. Inner ear and/or internal canal abnormalities, mumps hearing loss and congenital cytomegalovirus (CMV) infection have been identified as the major causes, while meningitis, auditory neuropathy spectrum disorder and endolymphatic hydrops are also considered as among the etiologies of ULHL. However, the etiology was indeterminate in more than half of the children with ULHL. MRI and CT studies of the inner ear should be performed for all children with ULHL. CMV DNA from the dried umbilical cord was detected in 9.1% of children with ULHL. No deafness gene mutations could be identified. Children with ULHL should be estimated by objective examinations, such as ABR, ASSR, OAE, et al., because they are sometimes diagnosed as having psychogenic hearing loss. Children with ULHL may also show a delay of speech development, learning problems, and psychological problems interfering with personal relationships, therefore, it is necessary to provide support to them. The results of HHIA and SF-36 tests have suggested that adult patients with unilateral sudden profound sensorineural hearing loss experience hearing handicap and deterioration of the QOL in terms of daily living, recently, the Born-Anchored Hearing Aid (BAHA) has been applied as a treatment for patients with unilateral deafness hearing loss, and cochlear implantation has also been used in some patients with unilateral deafness hearing loss and tinnitus.
The relationship between gender differences in hearing loss and severity of arteriosclerosis or diabetes mellitus was evaluated based on the data from the Anti-Aging Hearing Dock. This study was performed in 212 subjects (205 ears) who had no history of middle ear disease or any abnormal tympanic membrane findings. We measured the intima-media thickness of the carotid artery (IMT) as an index of arteriosclerosis. Multiple regression analysis by sex was performed to determine the relationship between hearing loss, and age, IMT and hemoglobin A1c as independent variables. The present study showed that the IMT was greater in the males than in the females and was closely correlated with the hearing level at 4-8kHz in the males. Furthermore, hearing level at higher frequencies was significantly poorer in the males than in the females. These findings suggest that arteriosclerosis is a strong factor aggravating presbyacusis at higher frequencies in the males. Diabetes mellitus was not related to the incidence of presbyacusis.
We propose a new analytical method of auditory evoked responses for a long series of music or voice sounds. This method is not to extract the target signal among the measured signals such as the averaging method, but to evaluate the correlativity between the sounds and the measured signals. For this purpose, we introduce a coherence function between the sound envelope and the measured signal. This function means that the correlativity is so low that the value is close to 0, and so high that the value is close to 1. To confirm the validity of this method, we carried out MEG measurements while the subject was listening to music. We confirmed that the measured signals had higher coherence values to listened sounds as compared to non-listened sounds. As an application of this method, we investigated the cocktail-party effect. We presented two-mixed sounds to the subject and measured the MEG signals. Subjects were instructed to note the side of the sounds. The results revealed higher values of the coherence function for the noticed as compared with that for the non-noticed sounds. This means that auditory response changes with attention and shows increase corresponding to the noted sounds. The proposed method was shown to be useful for investigation of the high auditory functions.
Developmental dyslexia is a specific learning disability that is neurological in origin. It is characterized by difficulties in reading and writing abilities. The case reported herein was that of a 7-year-old school boy who was suspected as having hearing impairment because of numerous errors of writing in school work. His audiogram showed normal hearing in both ears. The Screening Test of Reading and Writing for Japanese Primary School Children (STREW) revealed more marked writing impairment for isolated Hiragana and Katakana characters than for full words. He also showed greater difficulty in writing Katakana and Kanji than in writing Hiragana. It was assumed from some examinations that he had both disorders in phonological and visual information processing. A pediatric neurologist performed further examinations and diagnosed the condition as developmental dyslexia. For the diagnosis of this disorder, a cooperative approach with a specialist in pediatric neurology is recommended.
We investigated the changes in the prevalence of hearing impairment in primary school children in Sendai City from 1998 to 2008, and obtained the following results: 1) The number of subjects decreased in response to the reduction in the population of 6-to 12 year-old children in Japan, but increased slightly after 2005 in Sendai City. 2) The occurrence rate of hearing impairment decreased from 0.58% in 1998, with little fluctuation. This reduction was considered to be mainly attributable to the decreased occurrence of conductive hearing loss caused by secretory otitis media. 3) The prevalence of sensorineural hearing loss (SNHL) varied from 0.20% to 0.30%. 4) The prevalence of conductive hearing loss decreased gradually from 0.20% in 1998 to 0.04% in 2007. 5) While the prevalence of hearing impairment caused by secretory otitis media decreased each year, secretory otitis media still remains the main cause of conductive hearing loss. 6) The prevalence of functional hearing loss, including suspected cases, increased remarkably in latter years of the study period－this was the most remarkable finding of this study. 7) The incidence of unilateral severe SNHL was 0.04% or less, with no significant changes during the study period.
To evaluate the production of vowels after cochlear implantation, the first and second formant frequencies (F1 and F2) of the five Japanese vowels were measured in 4 children with cochlear implants. The results were compared between the children with deafness and severe hearing loss and those with normal hearing reported previously. In only one child, the formant frequencies of all five vowels were located within normal range. The other 3 children showed significant deviation from the normal range in some vowels. In all 4 children, the formant frequencies of /a/ distributed almost within the normal range. However, for the other 4 vowels (/i/, /u/, /e/ and /o/), deviation from the normal frequency range was observed in some children. When the ratio of the maximum and minimum values of F1 and F2 was compared with that in the normal hearing children, there was no significant difference of the F1. On the other hand, the values of F2 were smaller than those in normal children. The characteristics of the formant frequencies in the children with cochlear implants were similar to those in the children who were deaf with severe hearing loss. The utterance impairment seen in cochlear implant children can be explained by insufficient movement of the tongue as observed in children with deafness and severe hearing loss.
We investigated the relationship between hearing aid purchase decision making and the results of the adaptation test for hearing-aids. The guideline on hearing-aid adaptation tests recommends 8 tests, and 5 tests each were performed in 26 patients with sensorineural hearing loss at our facility, namely, the speech discrimination tests in quiet and noise, subjective test for environmental noise, threshold test for wearing hearing-aids and the questionnaire for hearing ability. The subjects' goodness of fit for hearing aids was estimated by performing these adaptation tests at 3 weeks after the first hearing-aid fitting. The results led to the purchase of hearing aids in 20 out of the 26 patients. There were no significant relationships between the results of the adaptation tests and the purchase rate of hearing aids. Our results indicated that adaptation to hearing aids is not the only factor motivating purchase of hearing aids.