Drullman R, Festen J M, Plomp R
Department of Oto-rhino-laryngology, Free University Hospital, Amsterdam, The Netherlands.
J Acoust Soc Am. 1994 Feb;95(2):1053-64. doi: 10.1121/1.408467.
The effect of smearing the temporal envelope on the speech-reception threshold (SRT) for sentences in noise and on phoneme identification was investigated for normal-hearing listeners. For this purpose, the speech signal was split up into a series of frequency bands (width of 1/4, 1/2, or 1 oct) and the amplitude envelope for each band was low-pass filtered at cutoff frequencies of 0, 1/2, 1, 2, 4, 8, 16, 32, or 64 Hz. Results for 36 subjects show (1) a severe reduction in sentence intelligibility for narrow processing bands at low cutoff frequencies (0-2 Hz); and (2) a marginal contribution of modulation frequencies above 16 Hz to the intelligibility of sentences (provided that lower modulation frequencies are completely present). For cutoff frequencies above 4 Hz, the SRT appears to be independent of the frequency bandwidth upon which envelope filtering takes place. Vowel and consonant identification with nonsense syllables were studied for cutoff frequencies of 0, 2, 4, 8, or 16 Hz in 1/4-oct bands. Results for 24 subjects indicate that consonants are more affected than vowels. Errors in vowel identification mainly consist of reduced recognition of diphthongs and of confusions between long and short vowels. In case of consonant recognition, stops appear to suffer most, with confusion patterns depending on the position in the syllable (initial, medial, or final).
针对听力正常的听众，研究了涂抹时间包络对噪声中句子的言语接受阈（SRT）以及音素识别的影响。为此，语音信号被分割成一系列频带（带宽为1/4、1/2或1倍频程），每个频带的幅度包络在截止频率为0、1/2、1、2、4、8、16、32或64Hz处进行低通滤波。36名受试者的结果表明：（1）在低截止频率（0 - 2Hz）下，窄处理带宽会导致句子清晰度严重下降；（2）高于16Hz的调制频率对句子清晰度的贡献微乎其微（前提是较低的调制频率完全存在）。对于高于4Hz的截止频率，SRT似乎与进行包络滤波的频率带宽无关。在1/4倍频程频带中，研究了截止频率为0、2、4、8或16Hz时对无意义音节的元音和辅音识别。24名受试者的结果表明，辅音比元音受影响更大。元音识别中的错误主要包括双元音识别率降低以及长元音和短元音之间的混淆。在辅音识别方面，塞音似乎受影响最大，混淆模式取决于其在音节中的位置（开头、中间或结尾）。
