title: Evaluation of speech intelligibility in short-reverberant sound fields.
abstract: OBJECTIVE
  The purpose of this study was to explore the differences in speech intelligibility in short-reverberant sound fields using deteriorated monosyllables. Generated using digital signal processing, deteriorated monosyllables can lack the redundancy of words, and thus may emphasize differences in sound fields in terms of speech clarity.
  
  
  METHODS
  Ten participants without any hearing disorders identified 100 monosyllables convolved with eight impulse responses measured in different short-reverberant sound fields (speech transmission index >0.6 and reverberation time <1s), and we compared speech recognition scores between normal and deteriorated monosyllables. Deterioration was produced using low-pass filtering (cut off frequency=1600Hz).
  
  
  RESULTS
  Speech recognition scores associated with the deteriorated monosyllables were lower than those for the normal monosyllables. In addition, scores were more varied among the different sound fields, although this result was not significant according to an analysis of variance. In contrast, the variation among sound fields was significant for the normal monosyllables. When comparing the intelligibility scores to the acoustic parameters calculated from eight impulse responses, the speech recognition scores were the highest when the reverberant/direct sound energy ratio (R/D) was balanced.
  
  
  CONCLUSIONS
  Although our deterioration procedure obscured differences in intelligibility score among the different sound fields, we have established that the R/D is a useful parameter for evaluating speech intelligibility in short-reverberant sound fields.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Nara Medical University, Japan. Electronic address: rshimo@naramed-u.ac.jp.
authors.forename: Ryota
authors.initials: R
authors.lastname: Shimokura
authors.affiliation: Life Science Centre of Tsukuba Advanced Research Alliance, University of Tsukuba, Japan.
authors.forename: Toshie
authors.initials: T
authors.lastname: Matsui
authors.affiliation: Department of Classroom Management, Faculty of Education of Future Generations, International Pacific University, Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Takaki
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Nara Medical University, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nishimura
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Nara Medical University, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yamanaka
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Nara Medical University, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hosoi
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D013065:Speech Intelligibility; D013067:Speech Perception
keywords: Deterioration procedure; Low-pass filtering; Short-reverberant sound field; Speech intelligibility