Centre for Research on Biological Communication Systems, Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road N., Mississauga, ON L5L 1C6, Canada.
Hear Res. 2012 Aug;290(1-2):55-63. doi: 10.1016/j.heares.2012.04.022. Epub 2012 May 16.
Older adults often find it more difficult than younger adults to attend to a target talker when there are other people talking. One possible reason for this difficulty is that it may take them longer to perceptually segregate the target speech from competing speech. This study investigated age-related differences in the time it takes to segregate target speech from either a speech spectrum noise masker or a babble masker (many people talking simultaneously). Specifically, we employed five different delays (0.1 s-1.1 s) between masker onset and target speech onset. Four signal-to-masker ratios were employed at each delay to determine the 50% thresholds for word recognition accuracy when target words were masked by either speech spectrum noise or multi-talker babble. Thresholds for word recognition decreased exponentially as a function of the masker-word-onset delay, at the same rate for younger and older adults, when the masker was speech spectrum noise. When the masker was babble, thresholds for younger adults decreased exponentially with delay at the same rate as they did when the masker was speech spectrum noise. The word recognition thresholds for older adults, however, did not appear to change over the range of delays explored in this study. In addition, the average difference between word recognition thresholds for younger and older adults (younger adult thresholds < older adult thresholds) was significantly larger when the masker was babble than when it was noise. These results indicate that older adults are as fast as younger adults at separating speech from a steady-state noise masker, but are not as capable as younger adults of taking advantage of the delayed onset of the speech target when the masker is babble. The potential contributions of age-related sensory and cognitive declines to these stream segregation effects are discussed. Finally, we conclude that age-related differences in the timeline for stream segregation contribute to the difficulties older adults experience in listening to speech in a background of babble.
老年人在有其他人说话时，往往比年轻人更难关注目标说话者。造成这种困难的一个可能原因是，他们可能需要更长的时间来感知将目标语音与竞争语音分离。本研究调查了在从语音频谱噪声掩蔽或语音混响掩蔽（许多人同时说话）中分离目标语音所需的时间方面，年龄相关的差异。具体来说，我们在掩蔽器起始和目标语音起始之间使用了五个不同的延迟（0.1s-1.1s）。在每个延迟处使用了四个信号与掩蔽器比率，以确定当目标词被语音频谱噪声或多说话者混响掩蔽时，单词识别准确率为 50%的阈值。当掩蔽器是语音频谱噪声时，单词识别阈值随掩蔽器-词起始延迟呈指数下降，年轻人和老年人的下降速率相同。当掩蔽器是语音混响时，年轻人的单词识别阈值随延迟呈指数下降，与掩蔽器是语音频谱噪声时的下降速率相同。然而，对于老年人，单词识别阈值似乎在本研究中探索的延迟范围内没有变化。此外，当掩蔽器是语音混响时，年轻人和老年人之间的单词识别阈值之间的平均差异（年轻人的阈值<老年人的阈值）明显大于当掩蔽器是噪声时。这些结果表明，老年人在将语音与稳态噪声掩蔽分离方面与年轻人一样快，但在掩蔽器是语音混响时，无法像年轻人那样利用语音目标的延迟起始来获得优势。讨论了与年龄相关的感官和认知下降对这些流分离效应的潜在贡献。最后，我们得出结论，流分离时间线上的年龄相关差异导致老年人在语音混响背景下听语音时遇到困难。
