Duchnowski P, Zurek P M
Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge 02139, USA.
J Acoust Soc Am. 1995 Dec;98(6):3170-81. doi: 10.1121/1.413806.
An algorithm to simulate the effects of sensorineural hearing impairment on speech reception was investigated. Like that described by Villchur [J. Acoust. Soc. Am. 62, 665-674 (1977)], this simulation employs automatic gain control in independent frequency bands to reproduce the elevated audibility thresholds and loudness recruitment that are characteristic of this type of loss. In the present implementation, band gains are controlled in an effort to simulate loudness recruitment directly, using recruitment functions that depend only on the magnitude of hearing loss in the band. In a preliminary evaluation, two normal-hearing subjects listened to the simulation matched to hearing losses studied previously [Zurek and Delhorne, J. Acoust. Soc. Am. 82, 1548-1559 (1987)] with noise-masking simulations. This evaluation indicated that the present automatic gain control simulation yielded scores roughly similar to those of both the hearing-impaired listeners and the masked-normal listeners. In the more-detailed evaluation, the performance of three listeners with severe sensorineural hearing loss on several speech intelligibility tests was compared to that of normal-hearing subjects listening to the output of the simulation. These tests included consonant-vowel syllable identification and sentence keyword identification for several combinations of speech-to-noise ratio, frequency-gain characteristic, and overall level. Generally, the simulation algorithm reproduced speech intelligibility well, though there was a clear trend for the simulation to result in better intelligibility than observed for impaired listeners when high-frequency emphasis placed more of the speech spectrum above threshold at higher frequencies. Also, the hearing-impaired listener with the greatest loss showed the largest discrepancies with the simulation. Overall, however, the simulation provides a very good approximation to speech reception by hearing-impaired listeners. The results of this study, together with previous studies of noise-making simulation, suggest that threshold elevation and recruitment, which are necessary features of a simulation of cochlear hearing loss, can also be largely sufficient for simulating the speech-reception performance of listeners with moderate to severe hearing impairments.
研究了一种用于模拟感音神经性听力损失对言语接受影响的算法。与Villchur [《美国声学学会杂志》62, 665 - 674 (1977)]所描述的类似，该模拟在独立频段中采用自动增益控制，以再现此类听力损失所特有的升高的可听度阈值和响度重振。在当前的实现中，通过使用仅依赖于频段内听力损失程度的重振函数，控制频段增益以直接模拟响度重振。在初步评估中，两名听力正常的受试者聆听了与先前研究[Zurek和Delhorne，《美国声学学会杂志》82, 1548 - 1559 (1987)]中所研究的听力损失相匹配的模拟，并伴有噪声掩蔽模拟。该评估表明，当前的自动增益控制模拟所得到的分数与听力受损听众以及掩蔽听力正常听众的分数大致相似。在更详细的评估中，将三名重度感音神经性听力损失患者在多项言语可懂度测试中的表现，与聆听模拟输出的听力正常受试者的表现进行了比较。这些测试包括针对几种信噪比、频率增益特性和总体水平组合的辅音 - 元音音节识别和句子关键词识别。总体而言，模拟算法能够较好地再现言语可懂度，不过当高频强调使更多的语音频谱在较高频率处高于阈值时，模拟结果显示出比受损听众更好的可懂度，这是一个明显的趋势。此外，听力损失最大的听力受损听众与模拟结果的差异最大。然而，总体而言，该模拟为听力受损听众的言语接受提供了非常好的近似。这项研究的结果，连同先前关于噪声生成模拟的研究表明，阈值升高和重振是模拟耳蜗性听力损失的必要特征，对于模拟中度至重度听力受损听众的言语接受表现也可能在很大程度上是足够的。
