Institute of Cognitive Neuroscience, National Central University, Jhongli County, Taoyuan City, Taiwan.
Institute of Cognitive Neuroscience, National Central University, Jhongli County, Taoyuan City, Taiwan.
Hear Res. 2018 Dec;370:155-167. doi: 10.1016/j.heares.2018.10.013. Epub 2018 Oct 19.
Binaural integration of interaural temporal information is essential for sound source localization and segregation. Current models of binaural interaction have shown that accurate sound localization in the horizontal plane depends on the resolution of phase ambiguous information by across-frequency integration. However, as such models are mostly static, it is not clear how proximate in time binaural events in different frequency channels should occur to form an auditory object with a unique lateral position. The present study examined the spectrotemporal window required for effective integration of binaural cues across frequency to form the perception of a stationary position. In Experiment 1, listeners judged whether dichotic frequency-modulated (FM) sweeps with a constant large nominal interaural delay (1500 μs), whose perceived laterality was ambiguous depending on the sweep rate (1500, 3000, 6000, and 12,000 Hz/s), produced a percept of continuous motion or a stationary image. Motion detection performance, indexed by d-prime (d') values, showed a clear effect of sweep rate, with auditory motion effects most pronounced for low sweep rates, and a punctate stationary image at high rates. Experiment 2 examined the effect of modulation rate (0.5, 3, 20, and 50 Hz) on lateralizing sinusoidally frequency-modulated (SFM) tones to confirm the effect of sweep rate on motion detection, independent of signal duration. Lateralization accuracy increased with increasing modulation rate up to 20 Hz and saturated at 50 Hz, with poorest performance occurring below 3 Hz depending on modulator phase. Using the transition point where percepts changed from motion to stationary images, we estimated a spectrotemporal integration window of approximately 150 ms per octave required for effective integration of interaural temporal cues across frequency channels. A Monte Carlo simulation based on a cross-correlation model of binaural interaction predicted 90% of the variance on perceptual motion detection performance as a function of FM sweep rate. Findings suggest that the rate of frequency channel convergence of binaural cues is essential to binaural lateralization.
双耳间时间信息的整合对于声源定位和分离至关重要。当前的双耳相互作用模型表明，在水平面上进行准确的声源定位取决于通过跨频整合来解析相位模糊信息的能力。然而，由于这些模型大多是静态的，因此不清楚不同频率通道中的双耳事件在时间上应该有多接近，才能形成具有独特横向位置的听觉对象。本研究考察了在不同频率之间有效整合双耳线索以形成固定位置感知所需的频谱时间窗口。在实验 1 中，听众判断具有恒定大名义耳间延迟（1500µs）的双声道频率调制（FM）扫频是否产生连续运动或固定图像的感知。运动检测性能，由 d-prime（d'）值表示，显示出扫频速率的明显影响，对于低扫频速率，听觉运动效应最为明显，而在高扫频速率下则出现点状固定图像。实验 2 考察了调制率（0.5、3、20 和 50Hz）对正弦调频（SFM）音调的侧化作用，以确认扫频速率对运动检测的影响，而不依赖于信号持续时间。随着调制率的增加，侧化精度增加，最高可达 20Hz，并在 50Hz 时饱和，而在 3Hz 以下取决于调制器相位，性能最差。使用感知从运动变为固定图像的过渡点，我们估计了大约 150ms 每八度的频谱时间整合窗口，用于在不同频率通道之间有效整合双耳时间线索。基于双耳相互作用的互相关模型的蒙特卡罗模拟预测了感知运动检测性能作为 FM 扫频速率函数的 90%的方差。研究结果表明，双耳线索的频率通道收敛率对于双耳侧化至关重要。
