Modulation masking release reduction as a function of time-compressed speech

ABSTRACT Purpose: to investigate the magnitude of the modulation masking release in sentence recognition as a function of compression level and modulation rate. Methods: sentences of the Brazilian Portuguese version of the Hearing in Noise Test sentences were used as stimulus. The sentence recognition thresholds were established as a function of speech compression level (0%, 33%, and 50%) in steady and modulated noise at different modulation rates (4, 10, 32 Hz). The analysis of variance was performed for repeated measures, using the 5% significance level. Results: sentence recognition thresholds were higher for higher compression levels in the different types of noise. However, thresholds were smaller for modulated noises. Also, the magnitude of modulation masking release decreased as speech compression level increased. Nevertheless, no difference was observed in compressed speech between different noise modulation rates, in relation to the speech compression level. Conclusion: the magnitude of the modulation masking release decreased as the speech time-compression increased. Also, the reductions in modulation masking release, in relation to the speech time-compression level, did not differ between the masking-noise modulation rates (4, 10, and 32 Hz).

摘要
研究目的：探究句子识别中调制掩蔽释放（modulation masking release）的幅度随言语压缩程度及调制速率的变化规律。
研究方法：采用巴西葡萄牙语版噪声下言语测试（Hearing in Noise Test, HINT）句子作为刺激材料。设置0%、33%、50%三种言语压缩水平，分别在稳态噪声与4、10、32 Hz三种调制速率的调制噪声环境下，建立句子识别阈值与言语压缩水平的函数关系。采用重复测量方差分析进行统计检验，显著性水平设定为5%。
研究结果：在两类噪声环境下，较高的言语压缩水平均对应更高的句子识别阈值；但调制噪声环境下的识别阈值更低。此外，调制掩蔽释放的幅度随言语压缩水平升高而降低。不过，在不同言语压缩水平下，不同噪声调制速率对压缩言语的识别阈值无显著差异。
研究结论：调制掩蔽释放的幅度随言语时间压缩程度提升而降低。同时，不同噪声调制速率（4、10、32 Hz）下，调制掩蔽释放随言语时间压缩水平变化的降幅无显著差异。