An audibility model of the headband trial with a bone conduction device in single-sided deaf subjects

Modelling the head-shadow effect compensation and speech recognition outcomes, we aimed to study the benefits of a bone conduction device (BCD) during the headband trial for single-sided deafened (SSD) subjects. This study is based on a database of individual patient measurements, fitting parameters, and acoustic BCD properties retrospectively measured on a skull simulator or from existing literature. The sensation levels of the Bone-Conduction and Air-Conduction sound paths were compared, modelling three spatial conditions with speech in quiet. We calculated the phoneme score using the Speech Intelligibility Index for the three conditions in quiet and seven in noise. Eighty-five SSD adults fitted with BCD during headband trial. According to our model, most subjects did not achieve a full head-shadow effect compensation with the signal at the BCD side and in front. The modelled speech recognition in the quiet conditions did not improve with the BCD on the headband. In noise, we found a slight improvement in some specific conditions and minimal worsening in others. Based on an audibility model, this study challenges the fundamentals of a BCD headband trial in SSD subjects. Patients should be counselled regarding the potential outcome and alternative approaches.

本研究通过对头影效应（head-shadow effect）补偿与语音识别结果进行建模，旨在探究单侧耳聋（single-sided deafened, SSD）受试者在头带式试戴试验中骨传导装置（bone conduction device, BCD）的获益效果。本研究的数据基础为包含患者个体测量数据、适配参数，以及通过颅骨模拟器回溯测得或取自现有文献的声学BCD特性的数据库。本研究对比了骨传导与气传导通路的感觉级，并针对安静环境下的语音场景建模了三种空间条件；同时采用言语可懂度指数（Speech Intelligibility Index），分别计算了安静环境下三种空间条件与噪声环境下七种空间条件的音素得分。本研究共纳入85名在头带试戴过程中佩戴BCD的单侧耳聋成年受试者。根据本研究的模型，当信号来自BCD侧及前方时，多数受试者未能实现完全的头影效应补偿；在安静环境下，佩戴头带式BCD并未使建模得到的语音识别性能得到提升。在噪声环境中，部分特定空间条件下的语音识别性能略有提升，其余条件则仅出现轻微下降。基于可听度模型，本研究对单侧耳聋受试者开展BCD头带试戴试验的核心原则提出了质疑，临床医师应向患者告知此类试验的潜在结局，并提供替代诊疗方案。