Abel S M, Armstrong N M, Giguère C
Hearing Research Laboratory, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
Scand Audiol. 1993;22(2):71-85. doi: 10.3109/01050399309046022.
Auditory perception with hearing protectors was assessed in three groups of subjects, two with normal hearing, but differing in age, and one with moderate bilateral sensorineural hearing loss. Individuals were tested with the ears unoccluded, and fitted with each of two level-dependent ear muffs and their conventional level-independent counterparts. One of the former devices provided limited amplification. In each of these five ear conditions, the threshold of audibility for one-third octave noise bands centered at 500, 1,000, 2,000 and 4,000 Hz, consonant discrimination, and word recognition were measured in quiet and in a continuous impulse noise background. The results showed that the attenuation of sounds (i.e. the difference between protected and unoccluded thresholds) in quiet did not vary as a function of age or hearing loss for any of the four protectors. In noise, the difference between protected and unoccluded listening was close to zero, as long as hearing was normal. With hearing loss as a factor, there was a significant increment in the protected threshold, the amount determined by the device. Word recognition in quiet was adversely affected in normal-hearing listeners by the three attenuating devices but improved in noise relative to unoccluded listening. Amplification had a deleterious effect for both consonant discrimination and word recognition in noise. In hearing-impaired listeners, speech perception was impeded by all four muffs but less so in quiet with limited amplification.
对三组受试者佩戴听力保护器后的听觉感知进行了评估，其中两组听力正常但年龄不同，另一组患有中度双侧感音神经性听力损失。受试者在耳朵未堵塞的情况下进行测试，然后佩戴两种与水平相关的耳罩及其传统的与水平无关的对应耳罩。前一种设备中的一种提供有限放大功能。在这五种耳部状况的每一种情况下，均在安静环境和连续脉冲噪声背景下测量了以500、1000、2000和4000赫兹为中心的1/3倍频程噪声带的可听阈、辅音辨别力和单词识别能力。结果表明，对于四种保护器中的任何一种，安静环境中声音的衰减（即佩戴保护器和未堵塞时阈值的差异）均不会随年龄或听力损失而变化。在噪声环境中，只要听力正常，佩戴保护器和未堵塞时的听力差异接近零。以听力损失为一个因素时，佩戴保护器时的阈值有显著增加，增加量由设备决定。在安静环境中，三种衰减设备对听力正常的受试者的单词识别有不利影响，但在噪声环境中相对于未堵塞时的听力有所改善。放大功能对噪声中的辅音辨别和单词识别都有有害影响。在听力受损的受试者中，所有四种耳罩都会妨碍言语感知，但在安静环境中且放大功能有限时妨碍较小。
