How does the brain restore missing speech information?

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K18705
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Psychology and related fields
• Research Institution: Kyushu University
• Principal Investigator: Ueda Kazuo 九州大学, 芸術工学研究院, 准教授 (80254316)
• Co-Investigator(Kenkyū-buntansha): Remijn GerardB. 九州大学, 芸術工学研究院, 准教授 (40467098) ; 中島 祥好 九州大学, 芸術工学研究院, 教授 (90127267)
• Project Period (FY): 2017-06-30 – 2020-03-31
• Keywords: 劣化音声知覚 / 音声修復 / 連続聴錯覚

Outline of Final Research Achievements

Intelligibility of temporally degraded speech was investigated with locally time-reversed speech (LTR) and its interrupted version (ILTR). Control stimuli comprising interrupted speech (I) were also included. Speech stimuli consisted of 200 Japanese meaningful sentences. In interrupted stimuli, speech segments were alternated with either silent gaps or pink noise bursts. The noise bursts had a level of -10, 0 or +10 dB relative to the speech level. Segment duration varied from 20 to 160 ms for ILTR sentences, but was fixed at 160 ms for I sentences. At segment durations of 40 and 80 ms, severe reductions in intelligibility were observed for ILTR sentences, compared with LTR sentences. A substantial improvement in intelligibility (30-33%) was observed when 40-ms silent gaps in ILTR were replaced with 0- and +10 dB noise. Noise with a level of -10-dB had no effect on the intelligibility.

Free Research Field

知覚心理学，聴覚心理学

Academic Significance and Societal Importance of the Research Achievements

音声を用いたコミュニケーションは，日常生活においては他の音声や音声以外の音が存在する中で行われることが普通である。そのような環境では，音声は他の音によって遮られたり，残響の影響を受けたりするが，それでも音声知覚は正常に行われている。本研究で行われた劣化音声の知覚に関する研究は，どのような劣化条件で知覚的修復が行われるのかを明らかにしたものである。音声知覚の仕組みを解明するという学術的意義に加えて，日常生活で用いられる人工内耳が満たすべき要件，あるいは限られた情報量で音声を伝送するための要件を明らかにする，という社会的意義がある。