Micheyl Christophe, Bernstein Joshua G W, Oxenham Andrew J
Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA.
J Acoust Soc Am. 2006 Sep;120(3):1493-505. doi: 10.1121/1.2221396.
Normal-hearing listeners' ability to "hear out" the pitch of a target harmonic complex tone (HCT) was tested with simultaneous HCT or noise maskers, all bandpass-filtered into the same spectral region (1200-3600 Hz). Target-to-masker ratios (TMRs) necessary to discriminate fixed fundamental-frequency (F0) differences were measured for target F0s between 100 and 400 Hz. At high F0s (400 Hz), asynchronous gating of masker and signal, presenting the masker in a different F0 range, and reducing the F0 rove of the masker, all resulted in improved performance. At the low F0s (100 Hz), none of these manipulations improved performance significantly. The findings are generally consistent with the idea that the ability to segregate sounds based on cues such as F0 differences and onset/offset asynchronies can be strongly limited by peripheral harmonic resolvability. However, some cases were observed where perceptual segregation appeared possible, even when no peripherally resolved harmonics were present in the mixture of target and masker. A final experiment, comparing TMRs necessary for detection and F0 discrimination, showed that F0 discrimination of the target was possible with noise maskers at only a few decibels above detection threshold, whereas similar performance with HCT maskers was only possible 15-25 dB above detection threshold.
通过同时呈现谐波复合音（HCT）或噪声掩蔽音来测试听力正常的听众“分辨出”目标谐波复合音音高的能力，所有声音均经过带通滤波，使其处于相同的频谱区域（1200 - 3600赫兹）。针对100至400赫兹之间的目标基频（F0），测量了辨别固定基频差异所需的目标与掩蔽音比率（TMR）。在高基频（400赫兹）时，掩蔽音和信号的异步选通、在不同基频范围内呈现掩蔽音以及减小掩蔽音的基频漂移，均能提高辨别性能。在低基频（100赫兹）时，这些操作均未显著提高辨别性能。这些发现总体上与以下观点一致：基于诸如基频差异和起始/结束异步性等线索来分离声音的能力，可能会受到外周谐波分辨能力的强烈限制。然而，也观察到了一些情况，即即便目标音和掩蔽音的混合中不存在外周可分辨的谐波，知觉分离似乎也是可能的。最后一项比较检测和基频辨别所需TMR的实验表明，使用噪声掩蔽音时，仅比检测阈值高几分贝就能辨别目标的基频，而使用谐波复合音掩蔽音时，只有比检测阈值高15 - 25分贝时才能有类似的辨别性能。
