Audiology Department, School of Life and Health Sciences, 1722Aston University, Birmingham, B4 7ET, UK.
Department of Electrical and Computer Engineering, 6612Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Trends Hear. 2022 Jan-Dec;26:23312165221117081. doi: 10.1177/23312165221117081.
Non-traumatic noise exposure has been shown in animal models to impact the processing of envelope cues. However, evidence in human studies has been conflicting, possibly because the measures have not been specifically parameterized based on listeners' exposure profiles. The current study examined young dental-school students, whose exposure to high-frequency non-traumatic dental-drill noise during their course of study is systematic and precisely quantifiable. Twenty-five dental students and twenty-seven non-dental participants were recruited. The listeners were asked to recognize unvoiced sentences that were processed to contain only envelope cues useful for recognition and have been filtered to frequency regions inside or outside the dental noise spectrum. The sentences were presented either in quiet or in one of the noise maskers, including a steady-state noise, a 16-Hz or 32-Hz temporally modulated noise, or a spectrally modulated noise. The dental students showed no difference from the control group in demographic information, audiological screening outcomes, extended high-frequency thresholds, or unvoiced speech in quiet, but consistently performed more poorly for unvoiced speech recognition in modulated noise. The group difference in noise depended on the filtering conditions. The dental group's degraded performances were observed in temporally modulated noise for high-pass filtered condition only and in spectrally modulated noise for low-pass filtered condition only. The current findings provide the most direct evidence to date of a link between non-traumatic noise exposure and supra-threshold envelope processing issues in human listeners despite the normal audiological profiles.
非创伤性噪声暴露已在动物模型中显示会影响包络线索的处理。然而，人类研究中的证据相互矛盾，这可能是因为这些措施没有根据听众的暴露情况进行具体参数化。本研究检查了年轻的牙科学院学生，他们在学习过程中接触高频非创伤性牙科钻头噪声是系统的，并且可以精确量化。招募了 25 名牙科学生和 27 名非牙科参与者。要求听众识别无声句子，这些句子仅包含用于识别的包络线索，并已过滤到牙科噪声频谱内或外的频率区域。句子在安静或噪声掩蔽器之一中呈现，包括稳态噪声、16Hz 或 32Hz 时变调制噪声或频谱调制噪声。牙科学生在人口统计学信息、听力筛查结果、扩展高频阈值或安静时的无声语音方面与对照组没有差异，但在调制噪声中的无声语音识别方面表现始终较差。群体差异取决于过滤条件。仅在高通滤波条件下，牙科组在时变调制噪声中的表现下降，仅在低通滤波条件下，牙科组在频谱调制噪声中的表现下降。尽管听力正常，但目前的发现提供了迄今为止最直接的证据，证明非创伤性噪声暴露与人听众的阈上包络处理问题之间存在联系。
