The functional imaging findings of cortical regions or their networks related to various steps or aspects of auditory processing are reviewed. The understanding of tonotopic organization of the primary auditory cortex has been deepened from a simple lateral-to-medial gradient model to more complex multiple-axes models. Auditory loudness processing may be performed in both the temporal auditory cortex and some areas outside the auditory cortex. Musical and speech sounds are processed in different areas within the superior temporal gyrus. Co-activations of the visual cortex and frontal motor related areas are found in addition to stronger and more extensive activation of the auditory cortices under difficult situations for auditory perception, such as hearing loss, low signal-to-noise ratio due to increased background noise, or hearing through cochlear implants. Functional brain imaging offers insights into the neurological mechanisms that underlie various difficulties arising from hearing loss, which may contribute to appropriate treatment and rehabilitation.
The developmental progress of the auditory behaviors (MAIS scores) and vocalization (MUSS scores) of 32 children using CI were investigated. Children who received CI before the age of four years were evaluated regularly in the preoperative phase and during the first 30 months of CI use, and the following results were obtained. 1) The average MAIS scores exceeded 70% after 18 months, and the average MUSS scores exceeded 70% after 30 months. 2) The rate of improvement of both the MAIS and MUSS scores varied according to the domain. 3) Both the MAIS and MUSS scores were less than 50% in all the domains in the initial improvement period. 4) In the intermediate improvement period of MAIS, the scores for the “request of auditory input” domain and “sound detection and discrimination” domain improved noticeably. 5) In the intermediate improvement period of MUSS, the scores for “intended vocalization” domain, “domestic use of speech” domain, and “daily use of speech” domain showed significant improvement. On the other hand, the scores for the “conversation strategy” domain remained at less than 50% even in the later improvement period. 6) To evaluate the CI performance, it is important to observe the improvement in each domain of auditory behavior and vocalization.
In TRT (Tinnitus Retraining Therapy) for patients with tinnitus and an awareness of hearing loss, acoustic therapy can be considered, however, there are patients who do not wish to continue wearing hearing aids. In this paper, we report our approaches to patients who were unable to continue TRT using hearing aids. We studied 13 patients (7 males and 6 females) who were unable to continue TRT using hearing aids out of the 44 patients (23 males and 21 females) who had tinnitus and visited the our hospital from April to December 2012. We evaluated the severity of tinnitus using the Tinnitus Handicap Inventory (THI), a visual analogue scale (VAS) (Hours [%] of the day during which the patients were worried about tinnitus), and the Hearing Handicap Inventory for Adults (HHIA). The reasons for the discontinuation of TRT using hearing aids were a feeling among the patients that it was ineffective, and the problem of cost. The former were patients with unilateral hearing loss who had a good ability for hearing on the healthy side and did not feel the necessity of wearing a hearing aid. When they wore a hearing aid on the affected side, they did not receive sufficient benefit and did not feel any improvement in the severity of the tinnitus because of an echo effect, due to which they gave up wearing the hearing aid. A refund was issued in the latter group. In these cases, even if the patients felt that their tinnitus had improved, they returned the hearing aid early because they felt it was expensive. Therefore, we consider that it is important to adjust a hearing aid so that external sounds can be fully input into the affected side in TRT using a hearing aid, and TRT can be continued with the device for 2-3 months.
We conducted a questionnaire survey of junior high school teachers to evaluate the study environment of cochlear-implant and hearing-aid users attending regular junior high schools in Fukushima Prefecture. In the present study, it was found that cochlear-implant and hearing-aid users have problems in hearing, low levels of academic achievement, and poor relationships with friends. However, their teachers can use fm systems, improve the education environment, and devise educational support plans and teaching plans only to a limited degree. Therefore, specialized institutions must provide school support in an organized and timely manner. We therefore propose a concrete division of roles for school support as follows. The Area Support Center of Fukushima prefectural school for the deaf will extend various direct supports, such as case conferences after class observation days for cochlear-implant and hearing-aid users and their junior high school teachers. The Fukushima Special Education Center will coordinate the support. Medical organizations will supply information regarding the hearing level and language skills of these children to the Area Support Center of Fukushima Prefectural School for the Deaf and the Fukushima Special Education Center.
Spectral and temporal information is critically important in characterizing sound signals. In this study of elderly patients with hearing loss, we investigated the associations of the gap detection threshold (GDT) and temporal modulation transfer function (TMTF), two common measures of auditory temporal resolution, with age and hearing level of speech. The results showed age-related decrease of both the GDT and TMTF. We also found that the TMTF peak sensitivity was strongly associated with speech clarity. These findings suggest that speech clarity is significantly influenced by the ability to detect temporal changes in sound pressure, which is represented by the peak sensitivity. On the other hand, the GDT and TMTF cutoff frequencies were barely relevant to speech perception. The findings of this study suggest that further efforts need to be made to improve temporal resolution in auditory loss and to develop hearing aid technologies that would modulate sound signals based on temporal components.
In this report, we present the results of our follow-up study of infants with hearing impairment who underwent consultation and subsequently received hearing aids at the Auditory and Cochlear Implant Center of Tokyo Medical University Hospital. The subjects were 24 infants who were diagnosed as having hearing loss at our center between January 2008 and June 2012. The average age at the first visit was 3.9 months. Newborn hearing screening was performed in 19 cases (79%). Detailed examinations of the distortion product otoacoustic emissions (DPOAE), auditory brainstem responses (ABR), and auditory steady state responses (ASSR) were used for the audiologic assessment. The average hearing levels were evaluated at the initial consultation and upon completion of the fitting process of the hearing aid. The period that elapsed between the initial use of the hearing aid and complete fitting of the hearing aid was recorded. The thresholds, gains and MOPs of the hearing aids were evaluated at the initial use and at completion of the fitting process. The average period that elapsed between the first use of the hearing aid and finalization of the fitting process was 6.5 months, and several problems occurred with the fitting of the hearing aids. The following issues were encountered in these patients: difficulty in evaluating the hearing levels (13 cases; 54%), ear mold (4 cases; 17%), howling noise (7 cases; 29%), fitting difficulties (20 cases; 83%), and difficulty in making the infant wear the hearing aid (9 cases; 38%). In the future, these issues should be addressed so that improvements can be made in these areas.