UCL Ear Institute, 332 Grays Inn Road, London WC1X 8EE, United Kingdom.
J Acoust Soc Am. 2012 Jul;132(1):327-38. doi: 10.1121/1.4718454.
The effects of forward and backward noise fringes on binaural signal detectability were investigated. Masked thresholds for a 12-ms, 250-Hz, sinusoidal signal masked by Gaussian noise, centered at 250 Hz, with bandwidths from 3 to 201 Hz, were obtained in N(0)S(0) and N(0)S(π) configurations. The signal was (a) temporally centered in a 12-ms noise burst (no fringe), (b) presented at the start of a 600-ms noise burst (backward fringe), or (c) temporally centered in a 600-ms noise burst (forward-plus-backward fringe). For noise bandwidths between 3 and 75 Hz, detection in N(0)S(0) improved with the addition of a backward fringe, improving further with an additional forward fringe; there was little improvement in N(0)S(π). The binaural masking-level difference (BMLD) increased from 0 to 8 dB with a forward-plus-backward fringe as noise bandwidths increased to 100 Hz, increasing slightly to 10 dB at 201 Hz. This two-stage increase was less pronounced with a backward fringe. With no fringe, the BMLD was about 10-14 dB at all bandwidths. Performance appears to result from the interaction of across-time and across-frequency listening strategies and the possible effects of gain reduction and suppression, which combine in complex ways. Current binaural models are, as yet, unable to account fully for these effects.
研究了正向和反向噪声条纹对双耳信号可听度的影响。在 N(0)S(0)和 N(0)S(π)配置中，获得了中心频率为 250 Hz、带宽为 3 至 201 Hz 的高斯噪声掩蔽的、持续时间为 12ms、250Hz 正弦信号的掩蔽阈值，该信号(a)在 12ms 噪声突发（无条纹）中时间居中，(b)在 600ms 噪声突发开始时呈现（反向条纹），或(c)在 600ms 噪声突发中时间居中（正向加反向条纹）。对于 3 至 75Hz 的噪声带宽，在 N(0)S(0)中添加反向条纹会提高检测效果，进一步添加正向条纹会进一步提高检测效果；在 N(0)S(π)中几乎没有改善。随着正向加反向条纹的增加，当噪声带宽增加到 100Hz 时，双耳掩蔽级差（BMLD）从 0 增加到 8dB，在 201Hz 时略有增加到 10dB。随着反向条纹的增加，这种两阶段的增加不太明显。没有条纹时，BMLD 在所有带宽下都约为 10-14dB。性能似乎源于跨时间和跨频率聆听策略的相互作用，以及增益降低和抑制的可能影响，这些影响以复杂的方式结合在一起。目前的双耳模型还不能完全解释这些影响。
