NAL-NL2 Empirical Adjustments
NAL-NL2 Empirical Adjustments
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DOI：
10.1177/1084713812468511
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发表时间：
2012-12-01
影响因子：
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通讯作者：
O'Brien, Anna
中科院分区：
文献类型：
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作者：
Keidser, Gitte;Dillon, Harvey;O'Brien, Anna
NAL- nl1是美国国家声学实验室（NAL）规定非线性增益的第一个程序，它是一个纯粹的理论推导公式，旨在最大限度地提高任何输入语音水平的语音清晰度，同时保持语音的总体响度等于或低于正常响度。通过对所选模型进行语音清晰度和响度预测的优化处理，得到该公式。使用更新的模型并对推导过程进行一些修改，以类似的方式获得了理论上推导的NAL-NL2公式。根据使用NAL-NL1作为基线反应的研究中收集的经验数据，对理论推导公式进行了进一步调整。具体来说，经验数据表明(a)女性助听器使用者比男性助听器使用者更喜欢低的总增益；(b)听力损失较轻微以上的助听器新使用者较有经验的助听器使用者更喜欢随着听力损失程度的增加而增加的增益，并需要长达2年的时间来适应有经验的助听器使用者所选择的增益水平；(c)单侧和双侧配戴助听器的使用者更喜欢总体增益水平的变化小于双侧矫正系数的估计；(d)成年人比儿童更喜欢低的总收益；(e)重度/重度听力损失患者在使用速效压缩装置时更倾向于低于预期的压缩比。本文对得出这些结论的文献和数据进行了总结和讨论，并描述了对理论推导的NAL-NL2公式进行调整的过程。
NAL-NL1, the first procedure from the National Acoustic Laboratories (NAL) for prescribing nonlinear gain, was a purely theoretically derived formula aimed at maximizing speech intelligibility for any input level of speech while keeping the overall loudness of speech at or below normal loudness. The formula was obtained through an optimization process in which speech intelligibility and loudness were predicted from selected models. Using updated models and applying some revisions to the derivation process, a theoretically derived NAL-NL2 formula was obtained in a similar way. Further adjustments, directed by empirical data collected in studies using NAL-NL1 as the baseline response, have been made to the theoretically derived formula. Specifically, empirical data have demonstrated that (a) female hearing aid users prefer lower overall gain than male users; (b) new hearing aid users with more than a mild hearing loss prefer increasingly less gain with increasing degree of hearing loss than experienced hearing aid users, and require up to 2 years to adapt to gain levels selected by experienced hearing aid users; (c) unilaterally and bilaterally fitted hearing aid users prefer overall gain levels that vary less than estimated by the bilateral correction factor; (d) adults prefer lower overall gain than children; and (e) people with severe/profound hearing loss prefer lower compression ratios than predicted when fitted with fast-acting compression. The literature and data leading to these conclusions are summarized and discussed in this article, and the procedure for implementing the adjustments to the theoretically derived NAL-NL2 formula is described.