Bashford James A, Warren Richard M, Lenz Peter W
Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201-0413.
Acoust Res Lett Online. 2000 Oct;1(2):31-36. doi: 10.1121/1.1329836.
Warren et al. (1995) reported over 90% intelligibility for everyday sentences reduced to a 1/3-octave band (center frequency 1,500 Hz, slopes 100 dB/octave, slow-rms peak levels 75 dB). To investigate the basis of this high intelligibility, Warren and Bashford (1999) partitioned the sentences. Surprisingly, the rectangular 1/3-octave passband had only 24% intelligibility, whereas the filter skirts separated by a 1/3-octave notch had an intelligibility of 83%, despite their severe spectral tilts. Experiment 1 of the present study substituted monosyllabic words for sentences. Wholeband intelligibility was 26%, the passband 4%, and the filter skirts 16%. Experiment 2 measured intelligibility for 1/3-octave sentences having peak levels ranging from 85 down to 35 dB. Whole band intelligibility ranged from 90% to 68%, and the filter skirt pairs had from two to four times the passband's intelligibility (which did not vary significantly with level). Hence, steep (100 dB/octave) filter skirts make the dominant contribution to intelligibility of nominally 1/3-octave speech across a wide range of presentation levels.
沃伦等人（1995年）报告称，对于简化为1/3倍频程频段（中心频率1500赫兹，斜率100分贝/倍频程，慢均方根峰值电平75分贝）的日常句子，可懂度超过90%。为了探究这种高可懂度的基础，沃伦和巴斯福德（1999年）对句子进行了划分。令人惊讶的是，矩形1/3倍频程通带的可懂度仅为24%，而被1/3倍频程陷波隔开的滤波器裙边的可懂度为83%，尽管它们有严重的频谱倾斜。本研究的实验1用单音节词替代了句子。全频段可懂度为26%，通带为4%，滤波器裙边为16%。实验2测量了峰值电平范围从85分贝降至35分贝的1/3倍频程句子的可懂度。全频段可懂度范围从90%到68%，滤波器裙边对的可懂度是通带的两到四倍（通带可懂度随电平变化不显著）。因此，陡峭（100分贝/倍频程）的滤波器裙边在很宽的呈现电平范围内对名义上1/3倍频程语音的可懂度起主要作用。
