Palmer Shannon B, Musiek Frank E
Department of Communication Sciences, University of Connecticut, Storrs, CT, USA.
J Am Acad Audiol. 2013 Jan;24(1):37-45. doi: 10.3766/jaaa.24.1.5.
Normal temporal processing is important for the perception of speech in quiet and in difficult listening situations. Temporal resolution is commonly measured using a behavioral gap detection task, where the patient or subject must participate in the evaluation process. This is difficult to achieve with subjects who cannot reliably complete a behavioral test. However, recent research has investigated the use of evoked potential measures to evaluate gap detection.
The purpose of the current study was to record N1-P2 responses to gaps in broadband noise in normal hearing young adults. Comparisons were made of the N1 and P2 latencies, amplitudes, and morphology to different length gaps in noise in an effort to quantify the changing responses of the brain to these stimuli. It was the goal of this study to show that electrophysiological recordings can be used to evaluate temporal resolution and measure the influence of short and long gaps on the N1-P2 waveform.
This study used a repeated-measures design. All subjects completed a behavioral gap detection procedure to establish their behavioral gap detection threshold (BGDT). N1-P2 waveforms were recorded to the gap in a broadband noise. Gap durations were 20 msec, 2 msec above their BGDT, and 2 msec. These durations were chosen to represent a suprathreshold gap, a near-threshold gap, and a subthreshold gap.
Fifteen normal-hearing young adult females were evaluated. Subjects were recruited from the local university community.
Latencies and amplitudes for N1 and P2 were compared across gap durations for all subjects using a repeated-measures analysis of variance. A qualitative description of responses was also included.
Most subjects did not display an N1-P2 response to a 2 msec gap, but all subjects had present clear evoked potential responses to 20 msec and 2+ msec gaps. Decreasing gap duration toward threshold resulted in decreasing waveform amplitude. However, N1 and P2 latencies remained stable as gap duration changed.
N1-P2 waveforms can be elicited by gaps in noise in young normal-hearing adults. The responses are present as low as 2 msec above behavioral gap detection thresholds (BGDT). Gaps that are below BGDT do not generally evoke an electrophysiological response. These findings indicate that when a waveform is present, the gap duration is likely above their BGDT. Waveform amplitude is also a good index of gap detection, since amplitude decreases with decreasing gap duration. Future studies in this area will focus on various age groups and individuals with auditory disorders.
正常的时间处理能力对于在安静环境和困难聆听情况下的语音感知至关重要。时间分辨率通常使用行为性间隙检测任务来测量，在此任务中患者或受试者必须参与评估过程。对于无法可靠完成行为测试的受试者而言，这很难实现。然而，最近的研究探讨了使用诱发电位测量来评估间隙检测。
本研究的目的是记录正常听力的年轻成年人对宽带噪声中间隙的N1 - P2反应。比较了N1和P2的潜伏期、波幅和形态对噪声中不同长度间隙的反应，以努力量化大脑对这些刺激的变化反应。本研究的目标是表明电生理记录可用于评估时间分辨率，并测量短间隙和长间隙对N1 - P2波形的影响。
本研究采用重复测量设计。所有受试者完成行为性间隙检测程序以确定其行为性间隙检测阈值（BGDT）。记录对宽带噪声中间隙的N1 - P2波形。间隙持续时间为20毫秒、比其BGDT高2毫秒以及2毫秒。选择这些持续时间来代表超阈值间隙、近阈值间隙和亚阈值间隙。
对15名正常听力的年轻成年女性进行了评估。受试者从当地大学社区招募。
使用重复测量方差分析比较了所有受试者在不同间隙持续时间下N1和P2的潜伏期和波幅。还包括对反应的定性描述。
大多数受试者对2毫秒的间隙未显示出N1 - P2反应，但所有受试者对20毫秒和2 +毫秒的间隙都有明显的诱发电位反应。间隙持续时间向阈值缩短导致波形波幅降低。然而，随着间隙持续时间的变化，N1和P2的潜伏期保持稳定。
在正常听力的年轻成年人中，噪声中的间隙可诱发N1 - P2波形。反应在比行为性间隙检测阈值（BGDT）高2毫秒时就存在。低于BGDT的间隙通常不会诱发电生理反应。这些发现表明，当出现波形时，间隙持续时间可能高于其BGDT。波形波幅也是间隙检测的一个良好指标，因为波幅随着间隙持续时间的缩短而降低。该领域未来的研究将聚焦于不同年龄组和患有听觉障碍的个体。
