Kim Hyojin, Epp Bastian
Auditory Physics Group, Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Lyngby, Denmark.
Front Neurosci. 2023 May 30;17:1102350. doi: 10.3389/fnins.2023.1102350. eCollection 2023.
Hearing ability is usually evaluated by assessing the lowest detectable intensity of a target sound, commonly referred to as a detection threshold. Detection thresholds of a masked signal are dependent on various auditory cues, such as the comodulation of the masking noise, interaural differences in phase, and temporal context. However, considering that communication in everyday life happens at sound intensities well above the detection threshold, the relevance of these cues for communication in complex acoustical environments is unclear. Here, we investigated the effect of three cues on the perception and neural representation of a signal in noise at supra-threshold levels.
First, we measured the decrease in detection thresholds produced by three cues, referred to as masking release. Then, we measured just-noticeable difference in intensity (intensity JND) to quantify the perception of the target signal at supra-threshold levels. Lastly, we recorded late auditory evoked potentials (LAEPs) with electroencephalography (EEG) as a physiological correlate of the target signal in noise at supra-threshold levels.
The results showed that the overall masking release can be up to around 20 dB with a combination of these three cues. At the same supra-threshold levels, intensity JND was modulated by the masking release and differed across conditions. The estimated perception of the target signal in noise was enhanced by auditory cues accordingly, however, it did not differ across conditions when the target tone level was above 70 dB SPL. For the LAEPs, the P2 component was more closely linked to the masked threshold and the intensity discrimination than the N1 component.
The results indicate that masking release affects the intensity discrimination of a masked target tone at supra-threshold levels, especially when the physical signal-to-noise is low, but plays a less significant role at high signal-to-noise ratios.
听力通常通过评估目标声音的最低可检测强度来衡量，通常称为检测阈值。被掩蔽信号的检测阈值取决于各种听觉线索，如掩蔽噪声的共调制、相位的双耳差异和时间背景。然而，考虑到日常生活中的交流发生在远高于检测阈值的声音强度下，这些线索在复杂声学环境中对交流的相关性尚不清楚。在此，我们研究了三种线索对阈上水平噪声中信号感知和神经表征的影响。
首先，我们测量了三种线索产生的检测阈值降低，即掩蔽释放。然后，我们测量了强度的最小可觉差（强度JND），以量化阈上水平目标信号的感知。最后，我们通过脑电图（EEG）记录晚期听觉诱发电位（LAEP），作为阈上水平噪声中目标信号的生理相关指标。
结果表明，这三种线索组合时，整体掩蔽释放可达约20dB。在相同的阈上水平，强度JND受掩蔽释放的调制，且在不同条件下有所不同。相应地，听觉线索增强了噪声中目标信号的估计感知，然而，当目标音调水平高于70dB SPL时，不同条件下并无差异。对于LAEP，P2成分比N1成分与掩蔽阈值和强度辨别更密切相关。
结果表明，掩蔽释放在阈上水平影响被掩蔽目标音调的强度辨别，特别是当物理信噪比低时，但在高信噪比时作用较小。
