Quar Tian Kar, Umat Cila, Chew Yong Yee
School of Rehabilitation Sciences, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.
J Am Acad Audiol. 2019 May;30(5):346-356. doi: 10.3766/jaaa.16150. Epub 2017 Oct 3.
The use of probe microphone measures in hearing aid verification is often neglected or not fully used by practitioners. Some practitioners rely on simulated gain and output provided by manufacturer's fitting software to verify hearing aids.
This study aims to evaluate the effectiveness of manufacturer's prefit procedure in matching the prescribed real-ear targets. It also aims to study its correlated impact on the predicted speech perception in children with severe and profound hearing loss.
This cross-sectional experiment was carried out by measuring the output of hearing aids based on prefit versus real-ear at low-, moderate-, and high-input levels. The predicted speech perception for different hearing aid fittings was determined based on the Speech Intelligibility Index (SII).
Sixteen children (28 ears) aged between 4 and 7 yr, with severe to profound sensorineural hearing loss took part in the study.
Two different types of hearing aids (Phonak and Unitron) were programmed based on their respective manufacturers' Desired Sensation Levels (DSL) v5 Child procedure. The hearing aids were then verified using coupler-based measurements and individual real-ear-to-coupler differences. The prefit outputs were compared with the DSL v5 Child-prescribed outputs at low-, moderate-, and high-input levels. The hearing aids were then adjusted to closely match the prescribed output. The SIIs were calculated for the fittings before and after adjustment.
Sixty four percent of fittings that were based on the prefit procedure achieved the optimal fit-to-targets, with less than 5-dB RMS deviations from the DSL v5 Child targets. After adjusting the hearing aids to attempt to meet the DSL v5 Child targets, 75% of the ears tested achieved the optimal fit-to-targets. On average, hearing aid outputs generated by the manufacturer's prefit procedure had good and reasonable agreement with the DSL v5 Child-prescribed outputs at low- and mid-frequencies. Nonetheless, at 4000 Hz, the hearing aid output mostly fell below the DSL v5 Child-prescribed outputs. This was still the case even after the hearing aid was adjusted to attempt to match with the targets. At low input level, some prefit outputs were found to be higher than the prescribed outputs. The deviations of prefit outputs from the prescribed outputs were dependent on the type of hearing aid and input levels. There was no significant difference between the SII calculated for fittings based on the prefit and adjusted fit.
Prefit procedure tends to produce outputs that were below the DSL v5 Child-prescribed outputs, with the largest mean difference at 4000 Hz. Even though the hearing aid gains were adjusted to attempt to match with the targets, the outputs were still below the targets. The limitations of hearing aids to match the DSL v5 Child targets at high-frequency region have resulted in no improvement in the children's predicted speech perception.
在助听器验证过程中，从业者往往忽视或未充分利用探针麦克风测量。一些从业者依靠制造商的拟合软件提供的模拟增益和输出进行助听器验证。
本研究旨在评估制造商的预拟合程序在匹配规定的真耳目标方面的有效性。同时研究其对重度和极重度听力损失儿童言语感知预测的相关影响。
本横断面实验通过在低、中、高输入水平下测量基于预拟合与真耳的助听器输出进行。基于言语可懂度指数（SII）确定不同助听器拟合的言语感知预测。
16名年龄在4至7岁之间、患有重度至极重度感音神经性听力损失的儿童（28只耳）参与了本研究。
根据各自制造商的期望感觉水平（DSL）v5儿童程序对两种不同类型的助听器（峰力和优利康）进行编程。然后使用基于耦合器的测量和个体真耳到耦合器差异对助听器进行验证。将预拟合输出与低、中、高输入水平下DSL v5儿童规定的输出进行比较。然后对助听器进行调整，使其更接近规定输出。计算调整前后拟合的SII。
基于预拟合程序的拟合中有64%实现了与目标的最佳匹配，与DSL v5儿童目标的均方根偏差小于5dB。在调整助听器以试图达到DSL v5儿童目标后，75%的受试耳实现了与目标的最佳匹配。平均而言，制造商的预拟合程序产生的助听器输出在低频和中频与DSL v5儿童规定的输出有良好且合理的一致性。然而，在4000Hz时，助听器输出大多低于DSL v5儿童规定的输出。即使在调整助听器以试图与目标匹配后，情况仍然如此。在低输入水平下，发现一些预拟合输出高于规定输出。预拟合输出与规定输出的偏差取决于助听器类型和输入水平。基于预拟合和调整后拟合计算的SII之间没有显著差异。
预拟合程序往往产生低于DSL v5儿童规定输出的输出，在4000Hz时平均差异最大。即使调整了助听器增益以试图与目标匹配，输出仍低于目标。助听器在高频区域匹配DSL v5儿童目标的局限性导致儿童言语感知预测没有改善。
