The educational process in school classrooms involves transmission of knowledge, exchange of ideas, and sharing of experiences via speech communication. A poor acoustic environment caused by noisy and reverberating conditions in the classroom causes deterioration of speech information, which would interfered with the cultivation of new knowledge and literacy in schoolchildren. In this paper, physical parameters of room acoustics, such as noise, reverberation and speech transmission index (STI), are outlined, and guidelines for classroom acoustics are introduced. The poor speech perception in the classroom caused by noise and reverberation affects the education of school children, especially those with a hearing problem. Acoustic treatments of the classroom, including installation of hearing-assistive devices of an audio induction loop, FM (frequency modulation of radio frequ-encies) and an infrared device, establishment of a sound field amplification system, and hearing aids with a directional microphone are suggested for improving the acoustic environment in classrooms.
In tinnitus retraining therapy (TRT) for patients with moderate to severe hearing loss, it is considered more appropriate to use other forms of acoustic therapy, including hearing aids, rather than tinnitus control instruments (TCI). The proposed use of hearing aids includes adjustment of the device settings to allow a low level of background input, switching off of the noise suppressor, and turning the directional function to non-directional input, thereby setting the program to allow ambient noise. This study reports the investigation of a patient who received TRT with hearing aids, involving the switching of programs. The patient was a 62-year-old female with severe hearing loss of sudden onset on the right side. The affected ear had been fitted with a hearing aid, and the gain setting on the hearing aid was adjusted to low-level amplification to allow background noise. The program was updated so that the following settings could be chosen as appropriate: when loud tinnitus is experienced; Program OFF (turn OFF noise suppression and turn OFF directional function), for clearer hearing, such as listening to a conversation; Program ON (turn ON noise suppression and turn ON directional function). The results indicated that patients with moderate to severe hearing loss showed a tendency to often select the Program OFF, which allowed noise input, in the early stage of the device use when tinnitus was strongly evident, and to often select the Program ON, which allowed better hearing of conversations, after the subject had become more accustomed to the tinnitus.
In bone conduction audiometry, the bone conduction noise method (modified Rainville method) can be used as an alternative to the ordinary test method using contralateral masking when it is difficult to obtain the accurate threshold of the ear being tested. In this study, it was first confirmed from the measurement of 24 otologically normal subjects that the lowering of the bone conduction threshold at low frequencies (occlusion effect) could be substantially eliminated by the use of an insert earphone with an open ear tip. We next postulated the reference level of bone conduction noise as being equal to the equivalent threshold force level+4dB, when the bone conduction noise is within the critical band width. Finally, bone conduction thresholds of 32 otologically normal subjects using the ordinary test method and the bone conduction noise method were obtained at 5 octave frequencies. As a result, both thresholds agreed, on average, within 5 dB at each frequency, suggesting the validity of the postulated reference level. It was expected that objective calibration of bone conduction noise according to that reference level, if provided by the manufacturer of the audiometer, would facilitate the clinical use of this method.
We investigated the efficiency of the Stenger test for subjects feigning unilateral hearing loss. The Stenger test was employed to estimate the genuine hearing thresholds at 250Hz, 1kHz and 4kHz in 11 normally hearing volunteer subjects feigning total unilateral hearing loss. The test was repeated under 4 conditions: 2 levels (10 and 5dBSL) of test tones presented to the normal ear, in the presence and absence of an earplug in the ear canal of the test ear simulating the complication of organic hearing loss. A `positive-Stenger-result' was obtained in all the subjects, indicating 100% sensitivity of the test for detecting feigning of unilateral hearing loss. The mean estimated hearing thresholds were almost equal to the true hearing thresholds. Estimation errors in the Stenger test were within 15dB (2SD) of the true hearing thresholds, irrespective of the test conditions. This estimation error was smaller than that previously reported using objective tests like ABR or ASSR. This result, with the fact that the Stenger test can be performed quickly without any special equipment, suggests that the Stenger test is more effective and useful for estimating genuine hearing thresholds in cases feigning unilateral hearing loss than the ABR or ASSR.
We report a case in which we diagnosed a carrier of a hearing loss gene. A 35-year-old man with hearing loss presented to us seeking to undergo genetic analysis for his sensory hearing loss. There were no persons among his family members or relatives, besides him, who suffered from hearing loss, except for his father who had mild bilateral hearing loss. The genetic analysis revealed that the patient was heterozygous for the G45E/Y136X mutation in the GJB2 gene. Then, his wife visited our hospital seeking carrier-state diagnosis of the hearing loss gene. Her hearing was normal. She wanted to understand the probability of hearing loss in her still unborn children. Although her pure-tone audiogram was almost normal, heterozygous 176-191del 16bp mutation of the GJB2 gene was detected. The rate of recurrence of hearing loss in their yet-to-be-born children was estimated to be 25-50%. It is necessary to perform carrier diagnosis according to the guideline on genetic testing and diagnosis, in cooperation with medical specialists in clinical hereditary disorders.