Smoorenburg G F
TNO Institute for Perception, Soesterberg, The Netherlands.
Acta Otolaryngol Suppl. 1990;469:38-46.
Assessment of hearing handicap is frequently based on hearing loss in the frequency region from 0.5 to 2.0 kHz. The region above 2 kHz, however, is important for hearing, particularly when one considers speech perception in conditions with ambient noise. The present study, based on 200 individuals (400 ears) with noise-induced hearing loss, shows that the average value of hearing loss at 2 and 4 kHz is the best simple predictor of the speech-reception threshold measured in noisy conditions. Speech perception is still impaired when the speech level and the level of the interfering noise exceed the hearing loss. This implies that calculations of speech intelligibility based on the articulation-index procedure are invalid. In these calculations it is assumed that only the speech-to-noise level distance (and not the extent of the hearing loss) determines the speech threshold when both the signal and the noise level exceed the hearing loss. An alternative model may be based on the assumption that the frequency channels in the region of the lesion are completely inoperative and that pure tones in this frequency region are detected because excitation spreads toward a region with normal sensitivity. Experimental verification and predictions based on this model show that this assumption is too rigorous. Frequency channels in the region of the lesion do become activated at high stimulus levels, but their contribution to speech perception deteriorates.
听力障碍的评估通常基于0.5至2.0千赫兹频率范围内的听力损失。然而，2千赫兹以上的区域对听力很重要，尤其是当考虑在有环境噪声的情况下的言语感知时。本研究基于200名患有噪声性听力损失的个体（400只耳朵），结果表明，2千赫兹和4千赫兹处听力损失的平均值是在噪声环境中测量的言语接受阈值的最佳简单预测指标。当言语水平和干扰噪声水平超过听力损失时，言语感知仍然会受到损害。这意味着基于清晰度指数程序的言语可懂度计算是无效的。在这些计算中，假设当信号和噪声水平都超过听力损失时，只有言语与噪声的水平差（而不是听力损失的程度）决定言语阈值。另一种模型可能基于这样的假设，即病变区域的频率通道完全不起作用，并且该频率区域的纯音是因为兴奋扩散到具有正常敏感性的区域而被检测到的。基于该模型的实验验证和预测表明，这一假设过于严格。病变区域的频率通道在高刺激水平下确实会被激活，但其对言语感知能力的贡献会降低。
