时域信息对健听青年在人工耳蜗模拟声下声调识别的影响

The Effect of Temporal Information in Cochlear Implant Analog Sounds on the Tone Recognition of Normal Hearing Young People

目的通过比较健听青年人在不同人工耳蜗模拟声下的声调识别正确率,探讨人工耳蜗时域信息编码对声调识别的影响。方法制作人工耳蜗模拟声:由播音员以正常语速发/a/、/o/、/e/、/i/、/u/、/ü/6个单韵母的四声,经过调整振幅包络和增加精细结构,编辑成500Hz以下不同采样精度(125、250……1 500pps)调整振幅包络和不调整振幅包络各288段(共576段)音频。用这些音频对30例健听青年进行声调识别测试,每人聆听6个韵母×4声调×振幅包络修改前后2组×4组500Hz以下不同采样精度共192段音频,分析其结果,分别比较两种不同时域信息对受试者声调识别正确率的影响。结果 (1)将不同时域精细结构合并考虑时,调整振幅包络趋向于基频(F0)对声调识别有显著作用:调整振幅包络后声调识别正确率(80.22%±16.32%)大于调整前(74.83%±20.24%)[F(1,9)=16.91,P=0.002];(2)将振幅包络合并考虑时,补充500 Hz以下频段精细结构对声调识别有影响[F(11,99)=38.86,P<0.001]:当采样精度<375pps时,声调识别成绩随采样精度的提高而显著提高(P<0.004),当采样精度≥375pps时,采样精度提高时声调识别成绩无显著改变(P>0.004);(3)调整振幅包络和精细结构之间有显著交互作用[F(11,99)=3.78,P<0.001]:当精细结构≤375pps时,调整振幅包络增加基频信息对声调识别有显著影响(P<0.05);当精细结构>375pps,随着时域信息精细程度增高,调整包络前后声调识别正确率的差值趋向于0(P>0.05)。结论 (1)人工耳蜗编码策略中调整振幅包络使之趋向F0有利于声调识别;(2)人工耳蜗编码策略中适当提高500Hz以下频率的采样精度能提高声调识别;(3)调整振幅包络趋向F0与补充500 Hz以下精细结构两种时域编码可同时运用于同一言语编码方案使声调清晰度最优化。

Objective By comparing the tone recognition rates for different cochlear implant(CI)analog sounds,the effects of the temporal coding strategy on tone recognition were investigated.Methods The professional announcer read6vowel(/a/,/o/,/e/,/i/,/u/,/ü/)of4different tones at a normal speed.After adjusting the amplitude envelope and increasing the fine structure,the audios with different sampling accuracy below500Hz(125,250……1500pps)were obtained,including288audio amplitude envelope adjusted and288not adjusted.Thirty young participants of normal hearing had tone recognition tests.The results and the tone recognition rates under two different temporal properties were compared.Results When the temporal fine structures were combined in consideration,the amplitude envelope as adjusted to match the fundamental frequency(F0)had a significant effect on the tone recognition.The tone recognition rate after amplitude envelope adjusted(80.22%±16.32%)was higher than before(74.83%±20.24%)\[F(1,9)=16.91,P=0.002\].When the amplitude envelopes were combined in consideration,changing the fine structure of the frequency below500Hz had a significant effect on the tone recognition\[F(11,99)=38.86,P<0.001\].When the sampling precision was<375pps,the tone recognition had improved remarkably with the improvement of sampling precision(P<0.004).When the sampling precision was≥375pps,the effect on the tone recognition was not significant(P>0.004).The interaction between changing amplitude envelopes and increasing the fine structure had a significant effect on the tone recognition\[F(11,99)=3.78,P<0.001\].When the fine structure≤375pps,adjustment on the amplitude envelope to increase the information of F0had a significant impact on the tone recognition(P<0.05).When the fine structure was>375pps,the difference of the tone recognition before and after the adjustment tended to0(P>0.05).Conclusion In the CI coding strategy,adjusting the amplitude envelope to get more F0information improves tone recognition.To a certain degree,the tone recognition improves when the sampling precision of frequency below500Hz is improved.Adjusting the amplitude envelope to F0and increasing the temporal fine structure below500Hz can be combined in the same speech coding strategy to optimize the tone recognition.