中川 誠司

<jats:p>Speech reception in the presence of competing sounds declines in middle age. Experiments on young normal-hearing listeners have revealed that speech reception performance in the presence of competing sounds is determined by the cumulative effects of two different types of masking: energetic masking and information masking. Here we examined how energetic and informational masking degrades speech reception in middle-aged adults. Fifteen young (seven males, eight females, 20–26 years) and seventeen middle-aged (four males, thirteen females, 47–57 years) listeners with normal hearing participated in the experiment. Speech reception in the presence of competing sounds was assessed by the Coordinated Response Measure. Participants were required to listen to a target phrase spoken by a female in the presence of noise or a single interfering phrase spoken by the same talker, same-sex talker, or different-sex talker. Speech reception performance was lower in middle-aged adults than young adults, regardless of the type of disturbing sounds. The performance differences between the same-talker and different-sex talker conditions, which reflects the effects of informational masking, was larger in middle-aged adults. These results suggest that both energetic and informational masking contributes to the degradation of speech reception in middle-aged adults.</jats:p>

<jats:p>Bone conduction (BC) has been applied to hearing aids for conductive hearing loss, earphones, and other audio devices including ones presenting sound to the face. One of the important characteristics of BC is the "occlusion effect (OE)", a phenomenon that low-frequency sound are perceived as being enhanced when the ear canal is occluded. Our previous study examining OE in facial parts reported that the OE in some facial parts was larger than OE in parts conventionally used. In this study, we conducted monosyllable articulation tests using bone-conducted speech with subjects' ear canal open and occluded, and investigated confusion in phoneme perception to evaluate the effect of OE on perception in the mastoid process, condylar process, nasal bone, and infraorbital region. The results showed that OE increased articulation. However, its effect varied depending on stimulus location and acoustic characteristics of the phonemes, and even confusions among unvoiced consonants even increased by OE. These findings are useful for optimizing BC devices using OE.</jats:p>

聴覚は視覚と並んでコミュニケーションに重要な感覚であり，特に言語コミュニケーションにおいては主要な役割を果たす．とりわけ乳幼児期の聴覚環境は言語能力の発達に重要であり，乳幼児期に十分な聴覚情報が入力されない場合は，発話能力も十分に形成されないことが多い．一方，乳幼児においては成人と同様の手法による聴覚検査や聴覚補償が困難であり，独特の技術やノウハウが必要となる．本発表では，新生児や乳幼児を対象とした聴力スクリーニングや聴力検査の手法や聴覚補償技術の現状と課題を紹介し，今後の研究開発を展望する．