Koehnke J, Cohen M F
J Acoust Soc Am. 1987 Mar;81(3):724-9. doi: 10.1121/1.394840.
This study was designed to investigate the effects of masker level and frequency on binaural detection and interaural time discrimination. Detection and interaural time discrimination of a 700-Hz sinusoidal signal were measured as a function of the center frequency and level of a narrow-band masking noise. The masker was a continuous, diotic, 80-Hz-wide noise that varied in center frequency from 250 to 1370 Hz. In the detection experiment, the signal was presented either diotically (NoSo) or interaurally phase reversed (NoS pi). In the interaural time discrimination experiment, the signal level needed to discriminate a 30-microseconds interaural delay was measured. As would be expected, the presence of the masker has a greater effect on NoSo detection than NoS pi detection, and for masker frequencies at or near the signal frequency. In contrast, interaural time discrimination can be improved by the presence of a low-level masker. Also, performance improves more rapidly as the signal/masker frequency separation increases for NoSo detection than for interaural time discrimination and NoS pi detection. For all three tasks, significant upward spread of masking occurs only at the highest masker level; at low masker levels, there is a tendency toward downward spread of masking.
本研究旨在调查掩蔽声强度和频率对双耳检测及双耳时间辨别能力的影响。以窄带掩蔽噪声的中心频率和强度为函数，测量了700赫兹正弦信号的检测及双耳时间辨别能力。掩蔽声为连续、双耳呈现、带宽80赫兹的噪声，其中心频率在250至1370赫兹之间变化。在检测实验中，信号以双耳同相（NoSo）或双耳反相（NoS pi）的方式呈现。在双耳时间辨别实验中，测量了辨别30微秒双耳延迟所需的信号强度。正如预期的那样，掩蔽声的存在对NoSo检测的影响比对NoS pi检测的影响更大，且在信号频率或接近信号频率的掩蔽声频率下尤为明显。相比之下，低强度掩蔽声的存在可改善双耳时间辨别能力。此外，对于NoSo检测，随着信号/掩蔽声频率间隔增加，性能提升比双耳时间辨别和NoS pi检测更快。对于所有这三项任务，仅在最高掩蔽声强度下才会出现明显的掩蔽上扩展；在低掩蔽声强度下，存在掩蔽下扩展的趋势。
