With the expansion of universal newborn hearing screening, otolaryngologists are increasingly being expected to evaluate and treat infants and very young children with hearing loss. However, audiologic evaluation in infants and children has several inherent limitations. Both distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) are widely used as adequate methods for universal newborn hearing screening. The presence of DPOAEs provides strong evidence of a normally functioning auditory periphery. ABR is considered to have high accuracy and a negligible false-negative rate. However, there is the possibility of congenital hearing loss not being identified by either test. Auditory neuropathy spectrum disorder (ANSD) cannot be detected by DPOAE screening. ABR screening is preferred for infants admitted to the NICU who are at a risk of neural hearing loss. Since the click-evoked ABRs lack frequency-specificity, they may underestimate the degree of hearing loss when the audiogram is sloping or unusual in shape. “Over-referral” rate of DPOAE screening is about 5%, mainly due to middle-ear effusion and a narrow external ear canal. NICU-treated or Down's syndrome infants have immature auditory pathways in some cases, resulting in a high threshold of ABR seen in the initial test. The combined use of objective testing and behavioral testing is recommended for pediatric audiologic assessment.
Abstract: From among the tests recommended in a guideline (2008) for evaluating the functions of a hearing aid, we conducted speech discrimination tests, calculated acoustic gain and aided HTL by frequency response and audiogram, and measured aided HTL in the sound field, together with observing the behavior in classroom and daily life for profoundly hearing-impaired young children aged between 3 and 5 years of age. Then, we discussed the appropriate ages, contents, methods and points to be considered in these tests. Our results suggested the following. 1) In the case of profoundly hearing-impaired young children, we could, to some degree, conduct tests for evaluating the functions of a hearing aid at the age of 3, and in more profoundly hearing-impaired cases, the tests could be conducted at the age of 5. 2) The speech recognition tests should be conducted after a specified period of auditory and language training, and the methods of stimulus presentation, response, involvement, and feedback, and the difficulty level of the tasks in these tests had to be adjusted according to the child's age, speech and language ability, and also the motivation and attitude toward the tests. 3) In the case of more profoundly hearing-impaired young children with, or suspected to have, developmental disorder, individual support adapted to the characteristics of the developmental disorder, developmental delay of speech perception and language, and emotional and psychological problems had to be provided in addition to the above-mentioned adjustments.
Stimulus frequency otoacoustic emission (SFOAE) was measured in 5 healthy volunteers using the suppression method. In this method, the SFOAE suppression level was calculated as the difference between the sound levels of the external ear canal to the probe tone alone and to the probe tone along with the suppressor tone having a frequency close to the probe tone. For a probe tone of 4000 Hz and 50 dB SPL, the suppression level of SFOAE to a 70 dB SPL suppressor was maximum when the suppressor frequency was in the range from nearby to 1200Hz above the probe frequency. As the suppressor level decreased, the SFOAE suppression level also significantly decreased when the suppressor frequency was lower than the probe tone, but scarcely so when the suppressor frequency was higher than the probe tone. These results were similar to those of previous studies. Further clinical applications of SFOAE, in addition to the mechanism of SFOAE suppression, are discussed.
We discussed the merging of tinnitus & hyperacusis from the viewpoint of uncomfortable level (UCL) and most comfortable level (MCL). We compared the UCL and MCL between a group of 38 tinnitus patients with no hearing loss (tinnitus group) and a group of 8 normal adults (control group). In the tinnitus group, transiently evoked otoacoustic emission (TEOAE), THI (Newman Japanese version), VAS, SRQD, and AIS were also examined. In the control group, the median UCL was 105dB and MCL was 55dB. The corresponding values in the tinnitus group were 95dB and 40dB. The results of statistical analysis revealed that both the UCL and MCL were significantly reduced in the tinnitus group, and that the severity of tinnitus was correlated with the degree of deterioration of the UCL and MCL. It was thought that the deterioration of UCL·MCL in the tinnitus group suggests the complication of hyperacusis. It is important to estimate hyperacusis by measuring the UCL and MCL during tinnitus therapy.
It is very important to detect the recruitment phenomenon in hearing-impaired patients, when adjusting the gain of a hearing aid. No frequency-specific objective audiometry for detecting the recruitment phenomenon in infants has been established. Therefore, the gain of hearing aids cannot be accurately adjusted in hearing-impaired infants. To resolve this problem, we attempted to detect the recruitment phenomenon using the auditory steady-state response (ASSR), which is an objective measurement with a high frequency-specificity. We examined 2 groups of subjects: 14 normal adults and 12 patients with unilateral hearing impairment, in whom the recruitment phenomenon was detected by the alternate binaural loudness balance test. We statistically compared the power of the response in the 2 groups. The power of the response increased with the stimulus intensity and was statistically significantly higher in the hearing-impaired subjects than in the normal subjects at 15, 20, 25, 30 and 35dB SL in both awake and sleeping subjects. The rate of increase of the power with the stimulus intensity was also statistically significantly higher in the hearing-impaired subjects than in the normal subjects. The results suggested that the higher rate of increase of power in the hearing-impaired patients than in normal adults reflects the recruitment phenomenon.
This study examined how the play behavior and communication of hearing-impaired preschoolers in inclusive settings were influenced by their hearing level, language ability and chronological age. Nine children with bilateral moderate to severe hearing loss aged between 3.4 and 6.1 years were observed during free play throughout the school year. They were divided into four play development groups—cooperative play (33.3%), solitary play (11.1%), parallel play (33.3%), and play with a nursery teacher (22.2%). The younger children were likely to have trouble receiving utterances from their hearing peers. Although the frequency of successful communication differed somewhat, all participants could communicate with their hearing classmates. The results suggest that communicative interaction between peers is influenced more by the chronological age than by the hearing level or language ability.
In this research, we examined the effect of sound sources other than noise for sound therapy in Tinnitus Retraining Therapy (TRT), with the cooperation of 10 patients who had had sufficient experience with a Sound Generator (SG). The results suggested the existence of some possibility of dispensability of SG broadband noise for sound therapy in TRT. The results in a case without hyperacusis suggested that a variety of sound sources had the potential of enough practicality for sound therapy. On the other hand, there were patients who had sound preferences, such as the sound of a “waterfall”, which resembles broadband noise, suggesting the effectiveness of SG. The sound of a “wave” had a tendency to be unsuitable for sound therapy, presumably due to the quiet part. It is therefore conceivable that the use of natural-environment sounds such as BGM, may be of greater value than the use of noise, from the viewpoint of creation of a comfortable environment for the bedroom, avoiding nighttime silence. We propose to carry out TRT with natural-environment sounds in the future, to investigate their efficacy.