Stilp Christian, Donaldson Gail, Oh Soohee, Kong Ying-Yee
Department of Psychological and Brain Sciences, University of Louisville, Louisville, Kentucky 40292, USA.
Department of Communication Sciences and Disorders, University of South Florida, PCD 1017, 4202 East Fowler Avenue, Tampa, Florida 33620, USA.
J Acoust Soc Am. 2016 Nov;140(5):3971. doi: 10.1121/1.4967445.
In simulations of electrical-acoustic stimulation (EAS), vocoded speech intelligibility is aided by preservation of low-frequency acoustic cues. However, the speech signal is often interrupted in everyday listening conditions, and effects of interruption on hybrid speech intelligibility are poorly understood. Additionally, listeners rely on information-bearing acoustic changes to understand full-spectrum speech (as measured by cochlea-scaled entropy [CSE]) and vocoded speech (CSE), but how listeners utilize these informational changes to understand EAS speech is unclear. Here, normal-hearing participants heard noise-vocoded sentences with three to six spectral channels in two conditions: vocoder-only (80-8000 Hz) and simulated hybrid EAS (vocoded above 500 Hz; original acoustic signal below 500 Hz). In each sentence, four 80-ms intervals containing high-CSE or low-CSE acoustic changes were replaced with speech-shaped noise. As expected, performance improved with the preservation of low-frequency fine-structure cues (EAS). This improvement decreased for continuous EAS sentences as more spectral channels were added, but increased as more channels were added to noise-interrupted EAS sentences. Performance was impaired more when high-CSE intervals were replaced by noise than when low-CSE intervals were replaced, but this pattern did not differ across listening modes. Utilizing information-bearing acoustic changes to understand speech is predicted to generalize to cochlear implant users who receive EAS inputs.
在电声刺激(EAS)模拟中,通过保留低频声学线索可提高声码语音清晰度。然而,在日常聆听环境中语音信号常被打断,而打断对混合语音清晰度的影响却鲜为人知。此外,听众依靠携带信息的声学变化来理解全频谱语音(通过耳蜗标度熵[CSE]测量)和声码语音(CSE),但听众如何利用这些信息变化来理解EAS语音尚不清楚。在此,听力正常的参与者在两种条件下聆听了具有三到六个频谱通道的噪声声码句子:仅声码器(80 - 8000赫兹)和模拟混合EAS(500赫兹以上声码;500赫兹以下原始声学信号)。在每个句子中,四个包含高CSE或低CSE声学变化的80毫秒间隔被语音形状噪声所取代。正如预期的那样,保留低频精细结构线索(EAS)时表现有所改善。对于连续的EAS句子,随着添加更多频谱通道,这种改善会降低,但对于噪声打断的EAS句子,随着添加更多通道,改善会增加。当高CSE间隔被噪声取代时,表现比低CSE间隔被取代时受损更严重,但这种模式在不同聆听模式下并无差异。预计利用携带信息的声学变化来理解语音可推广到接受EAS输入的人工耳蜗使用者。