第一部分  先后天单侧耳聋患者噪声下言语识别能力的差异

目的

系统比较先天性与后天性单侧感音神经性耳聋患者噪声下言语识别能力的差异，以探讨听觉剥夺发生时间对中枢代偿的影响。

方法

采用横断面研究将62例单侧耳聋患者按发病时间分为先天性与后天性单侧耳聋，同时匹配31例听力正常受试者作为对照。对于噪声位于前方，信号分别位于前方、患侧、健侧三种条件下，采用自适应法测定各组在不同方向的噪声下言语识别阈，并在信号和噪声均位于前方且信噪比为0dB和-2dB的条件下测试言语识别率。比较三组间噪声下言语识别能力的差异并且比较不同耳聋侧别是否对耳聋患者产生显著影响。

结果

各种方位条件下，后天性单侧耳聋患者的言语识别阈值均显著高于先天性单侧耳聋患者，两组患者的言语识别阈值均显著高于正常听力者。在信噪比为0 dB及-2 dB且噪声、信号均位于前方的条件下，后天性单侧耳聋患者的言语识别率显著低于先天性单侧耳聋患者，且仅后天组与正常听力组之间存在显著差异，而先天组与正常听力组间差异不显著。此外，左耳与右耳先天性单侧耳聋患者在言语识别阈值方面亦表现出显著差异。

结论

先天性单侧耳聋个体在噪声环境下的言语识别能力优于后天性耳聋者，提示其有更好的中枢功能代偿。同时，耳聋侧别亦可能影响先天性单侧耳聋者的言语识别表现。

第二部分 单侧耳聋患者听觉与视觉辨别加工中的功能重塑

目的 ​

单侧耳聋是部分听觉剥夺的一种典型表现。已有的研究证实完全听觉剥夺会引发显著的跨感官模态神经重塑，但部分听觉剥夺状态下，机体如何平衡残余的听觉功能与其他感觉代偿重塑的关系尚不明确。既往研究因受试群体存在异质性或任务设计有差异导致结论缺乏一致性。本研究旨在同一先天性单侧耳聋群体中研究感觉剥夺后视、听两种模态各层级神经加工的重塑特征。

方法

本研究共纳入37例先天性单侧耳聋患者与32例听力正常对照者，分别在执行视、听Oddball范式任务的同时记录其脑电图。听觉任务中，两组均为双耳给声。通过分析早期外源性成分以及晚期内源性成分，观察部分听觉剥夺对单侧耳聋患者在视听任务中各级神经活动的影响。所分析的外源性成分包括：听觉N1、 P2、失匹配负波（mismatch negativity，MMN）; 视觉N1、视觉失匹配负波（visual mismatch negativity，vMMN）。所分析的内源性成分包括：听觉N2、P3；视觉N2、P3。

结果

听觉任务中，单侧耳聋与听力正常组均记录到上述早期外源性与晚期内源性成分。单侧耳聋组早期外源性成分N1、P2、MMN振幅均较对照组显著降低，潜伏期组间无差异。晚期内源性成分N2、P3振幅与潜伏期均无组间差异。视觉任务中，两组均记录到上述早期与晚期的各成分，单侧耳聋组外源性成分N1振幅较对照组显著增加，潜伏期无差异。早期视觉vMMN及晚期内源性成分N2、P3振幅与潜伏期均无组间差异。

结论

单侧耳聋患者低级与高级加工阶段的神经重塑有差异。其功能性重塑主要发生在早期感觉加工阶段，表现为听觉神经活动的减弱及视觉神经活动的代偿性增强，而在更高级的辨别加工阶段，听觉和视觉两种通道均未见显著影响。该结果不仅澄清了以往研究结果不一致的原因，也为理解部分感觉剥夺条件下的神经重塑建立了分层框架。

Part Ⅰ: Differences in Speech Recognition in Noise between Patients with Congenital and Acquired Single-Sided Deafness

Objective

This study aim to systematically compare speech recognition performance in noise between individuals with congenital and acquired single-sided sensorineural deafness, in order to investigate the impact of the onset time of auditory deprivation on central compensation.

Methods

In this cross-sectional study, 62 individuals with single-sided deafness (SSD) were classified into congenital and acquired groups based on the time of onset. Thirty-one age- and sex-matched normal-hearing individuals were included as controls. Speech recognition thresholds in noise (NRT) were measured using an adaptive procedure under three spatial conditions: noise from the front with speech from the front, the deaf side, or the normal-hearing side. Speech recognition scores (SRS) were assessed at signal-to-noise ratios (SNR) of 0 dB and –2 dB when both signal and noise originated from the front. Group differences in speech recognition performance under various spatial and SNR conditions were analyzed. Additionally, the influence of deaf-sidedness (left vs. right) was evaluated within the SSD groups.

Results

Under all spatial configurations, participants with acquired SSD demonstrated significantly higher NRTs than those with congenital SSD, and both SSD groups had significantly elevated thresholds compared to normal-hearing controls. At both 0 dB and –2 dB SNRs with frontal signal and noise, individuals with acquired SSD had significantly lower SRSs than those with congenital SSD. Notably, a significant difference was observed only between the acquired SSD group and controls, while no significant difference was found between the congenital SSD group and controls. Furthermore, among individuals with congenital SSD, those with left-ear deafness exhibited significantly different NRTs compared to those with right-ear deafness.

Conclusion

Individuals with congenital SSD exhibit better speech recognition performance in noise compared to those with acquired SSD, suggesting more effective central compensatory plasticity. In addition, the side of deafness may also affect speech recognition outcomes in congenital SSD.

Part II: Functional Reorganization in Auditory and Visual Discrimination Processing in Single-sided Deafness

Objective

Single-sided deafness (SSD) represents a typical form of partial auditory deprivation. Previous studies have demonstrated that complete auditory deprivation induces significant cross-modal neural reorganization; however, how the brain balances residual auditory function with compensatory plasticity in other sensory modalities under conditions of partial deprivation remains unclear. Inconsistencies in prior findings may be attributed to heterogeneity in subject populations and variations in task paradigms. The present study aimed to investigate modality-specific and stage-specific patterns of neural reorganization following sensory deprivation within a homogeneous group of individuals with congenital SSD.

Methods

Thirty-seven individuals with congenital SSD and thirty-two normal-hearing controls underwent electroencephalography (EEG) recording while performing auditory and visual oddball tasks. In the auditory task, binaural stimulation was used for both groups. Neural responses were analyzed for both early exogenous and late endogenous components to assess the impact of partial auditory deprivation on auditory and visual processing. The exogenous components analyzed included auditory N1, P2, and mismatch negativity (MMN), as well as visual N1 and visual mismatch negativity (vMMN). The endogenous components included auditory N2 and P3, and visual N2 and P3.

Results

In the auditory task, both groups exhibited identifiable abovementioned early and late ERP components. Compared to controls, the congenital SSD group showed significantly reduced amplitudes of early auditory components (N1, P2, MMN), with no significant differences in latencies. For late auditory components (N2, P3), no significant differences in amplitude or latency were observed between groups. In the visual task, both early and late components were present in both groups. Notably, the SSD group demonstrated significantly increased amplitudes of the early visual N1 component compared to controls, while latencies remained similar. No group differences were found for vMMN, visual N2, or P3 in terms of amplitude or latency.

Conclusion

Individuals with congenital SSD exhibit distinct neural reorganization across different sensory processing stages. Functional reorganization appears primarily at early sensory stages, characterized by reduced auditory and enhanced visual neural activity, suggesting compensatory cross-modal plasticity. In contrast, higher-order discriminative processing remains largely unaffected in both auditory and visual modalities. These findings clarify discrepancies in the existing literature and provide a hierarchical framework for understanding neuroplasticity under conditions of partial sensory deprivation.