Hedrick M S, Rice T
Department of Audiology & Speech Pathology, University of Tennessee, Knoxville 37996-0740, USA.
J Speech Lang Hear Res. 2000 Oct;43(5):1174-84. doi: 10.1044/jslhr.4305.1174.
Previous studies have shown that altering the amplitude of a consonant in a specific frequency region relative to an adjacent vowel's amplitude in the same frequency region will affect listeners' perception of the consonant place of articulation. Hearing aids with single-channel, fast-acting wide dynamic range compression (WDRC) alter the overall consonant-vowel (CV) intensity ratio by increasing consonant energy. Perhaps one reason WDRC has had limited success in improving speech recognition performance is that the natural amplitude balances between consonant and vowel are altered in crucial frequency regions, thus disturbing the aforementioned amplitude cue for determining place of articulation. The current study investigated the effect of a WDRC circuit on listeners' perception of place of articulation when the relative amplitude of consonant and vowel was manipulated. The stimuli were a continuum of synthetic CV syllables stripped of all place cues except relative consonant amplitudes. Acoustic analysis of the CVs before and after hearing aid processing showed a predictable increase in high-frequency energy, particularly for the burst of the consonant. Alveolar bursts had more high-frequency energy than labial bursts. Twenty-five listeners with normal hearing and 5 listeners with sensorineural hearing loss labeled the consonant sound of the CV syllables in unaided form and after the syllables were recorded through a hearing aid with single-channel WDRC. There were significantly more listeners who were unable to produce a category boundary when labeling the aided stimuli. Of those listeners who did yield a category boundary for both aided and unaided stimuli, there were significantly more alveolar responses for the aided condition. These results can be explained by the acoustic analyses of the aided stimuli.
先前的研究表明，相对于同一频率区域中相邻元音的幅度，改变特定频率区域中辅音的幅度会影响听众对辅音发音位置的感知。具有单通道、快速作用宽动态范围压缩（WDRC）功能的助听器通过增加辅音能量来改变辅音-元音（CV）的整体强度比。WDRC在改善语音识别性能方面取得的成功有限，可能的一个原因是，在关键频率区域中，辅音和元音之间的自然幅度平衡被改变，从而干扰了上述用于确定发音位置的幅度线索。本研究调查了在操纵辅音和元音的相对幅度时，WDRC电路对听众发音位置感知的影响。刺激材料是一系列合成的CV音节，去除了除辅音相对幅度之外的所有发音位置线索。对助听器处理前后的CV音节进行声学分析，结果显示高频能量有可预测的增加，尤其是辅音的爆发音部分。齿龈爆发音比唇音爆发音具有更多的高频能量。25名听力正常的听众和5名感音神经性听力损失的听众对未佩戴助听器时以及通过单通道WDRC助听器录制后的CV音节的辅音发音进行了标注。在标注佩戴助听器后的刺激材料时，无法产生类别边界的听众明显更多。在那些对佩戴助听器和未佩戴助听器的刺激材料都产生了类别边界的听众中，佩戴助听器情况下齿龈音的反应明显更多。这些结果可以通过对佩戴助听器后的刺激材料的声学分析来解释。
