Turner C W, Souza P E, Forget L N
Syracuse University New York 13244-2280, USA.
J Acoust Soc Am. 1995 Apr;97(4):2568-76. doi: 10.1121/1.411911.
The temporal acuity of listeners with sensorineural hearing loss is currently a matter of some controversy. In this study, the ability of normal-hearing and hearing-impaired listeners to utilize temporal cues of speech was measured directly. In addition to natural (unprocessed) nonsense syllables, several processed-speech conditions were employed. Nonsense syllables were digitally processed to remove the original spectral information, resulting in a time-varying speech envelope amplitude modulating a noise carrier. The processed-speech conditions were the envelope of a broadband speech signal modulating a broadband noise, a low-pass speech signal modulating a low-pass noise, a high-pass speech signal modulating a high-pass noise, and a two-channel signal comprised of the low- and high-pass modulated signals combined. Recognition of the envelope stimuli in quiet and also in modulated and steady noise backgrounds was tested. Listeners were tested at presentation levels yielding their maximum performance on a syllable recognition task. The hearing-impaired listeners performed more poorly on a recognition task than the normal-hearing listeners for unprocessed speech signals. However, for listeners with hearing losses of either flat or sloping configuration, there was no significant deficit in their ability to use temporal cues in speech, even in frequency regions of hearing loss up to 70 dB HL. These results demonstrate that moderate to severe sensorineural hearing loss does not impair the temporal (nonspectral) acuity of listeners in terms of speech recognition, when audibility of the stimuli is compensated for.
感音神经性听力损失患者的时间分辨能力目前存在一定争议。在本研究中，直接测量了听力正常和听力受损受试者利用语音时间线索的能力。除了自然（未处理）的无意义音节外，还采用了几种处理后的语音条件。对无意义音节进行数字处理以去除原始频谱信息，从而产生一个随时间变化的语音包络，该包络对噪声载波进行幅度调制。处理后的语音条件包括：宽带语音信号的包络调制宽带噪声、低通语音信号调制低通噪声、高通语音信号调制高通噪声，以及由低通和高通调制信号组合而成的双通道信号。测试了在安静环境以及调制和稳定噪声背景下对包络刺激的识别能力。在音节识别任务中，以能使受试者表现最佳的呈现水平对他们进行测试。对于未处理的语音信号，听力受损受试者在识别任务中的表现比听力正常受试者差。然而，对于平坦或斜坡型听力损失的受试者，即使在高达70 dB HL的听力损失频率区域，他们利用语音时间线索的能力也没有显著缺陷。这些结果表明，当中等至重度感音神经性听力损失患者的刺激可听度得到补偿时，其在语音识别方面的时间（非频谱）分辨能力并未受损。
