The Effect of Temporal Information in Cochlear Implant Analog Sounds on the Tone Recognition of Normal Hearing Young People / 听力学及言语疾病杂志

ABSTRACT

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 read 6 vowel (/a/,/o/,/e/,/i/,/u/,/ü/) of 4 different tones at a normal speed .After adjusting the am-plitude envelope and increasing the fine structure ,the audios with different sampling accuracy below 500 Hz(125 ,250? ?1500 pps) were obtained ,including 288 audio amplitude envelope adjusted and 288 not adjusted .Thirty young participants of normal hearing had tone recognition tests .The results and the tone recognition rates under two dif-ferent temporal properties were compared .Results When the temporal fine structures were combined in considera-tion ,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 consider-ation ,changing the fine structure of the frequency below 500 Hz had a significant effect on the tone recognition [F (11 ,99)=38 .86 ,P<0 .001] .When the sampling precision was <375 pps ,the tone recognition had improved re-markably with the improvement of sampling precision (P<0 .004) .When the sampling precision was ≥375 pps , the effect on the tone recognition was not significant (P>0 .004) .The interaction between changing amplitude en-velopes 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 ≤375 pps ,adjustment on the amplitude envelope to increase the information of F0 had a significant impact on the tone recognition (P<0 .05) .When the fine structure was >375 pps ,the difference of the tone recognition before and after the adjustment tended to 0 (P>0 .05) .Conclusion In the CI coding strate-gy ,adjusting the amplitude envelope to get more F0 information improves tone recognition .To a certain degree ,the tone recognition improves when the sampling precision of frequency below 500 Hz is improved .Adjusting the ampli-tude envelope to F0 and increasing the temporal fine structure below 500 Hz can be combined in the same speech coding strategy to optimize the tone recognition .