認知機能低下例へのマスキング法による発声アプローチ

Voice exercise using the masking method for cognitively impaired patients

　脳血管障害などにより著しい認知機能低下を伴う音声障害2例に，Lombard効果を利用した訓練法であるマスキング法を試みた．2例とも簡単な会話は可能であったが，著明な声の大きさの低下がみられた．ごく単純な指示理解も難しいことからアクセント法などの訓練法は実施困難であり，通常のマスキング法に工夫を加え，①95dBSPLのホワイトノイズをヘッドホンで聞かせ声の大きさの増大を確認，②ノイズ音量を減衰させ，増大した声の大きさを維持可能な音量で固定，③その状態で自由会話を約15分間継続した．2例とも当初はノイズ下でのみ声の大きさが増大，数日後ノイズoffでも声の大きさの増大を短時間維持可能となり，最終的に日常でも定着した．即時効果などからこれらの増大に本法が影響した可能性は高いと考えられた．伝達意図が比較的保たれたことがLombard効果成立の可能性として考えられた．

　The masking method, which is a voice training method using the Lombard effect, was attempted in two patients with voice disorders accompanied by significant cognitive impairment due to cerebrovascular disease, etc.　Although they engaged in simple conversations, obvious decrease in the vocal loudness was noted for both patients.　As it was difficult for them to understand even simple directions, widely-used training methods such as the accent method, etc.　were not feasible.　Therefore, the following modifications of the ordinary masking method were attempted:1．Observe the increase in the vocal loudness while they are hearing white noise at 95dBSPL with headphones;2．Reduce the noise volume and fix the increased vocal loudness at the volume which can be maintained;and 3．Continue free conversation under this condition for approximately 15 minutes.　The vocal loudness increased only under the noise at the beginning in both patients.　After a few days, they became able to maintain the increased vocal loudness for a short period of time when the white was noise switched off, and the vocal loudness was eventually stabilized in their daily life.　Considering the immediacy effects, it was thought that the modified method had effectively contributed to this increase in vocal loudness.　It seemed that the Lombard effect was successfully achieved probably because their intension of communication was relatively maintained.