Abel S M, Spencer D L
Hearing Research Laboratory, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
Scand Audiol. 1997;26(3):155-67. doi: 10.3109/01050399709074989.
The benefits of active noise reduction (ANR) hearing protectors were assessed in two groups of normal-hearing subjects, under and over the age of 40 years, and one group with bilateral high-tone hearing loss. Subjects were tested with the ears unoccluded and fitted with conventional sound attenuating E-A-R foam plugs, E-A-R HI-FI plugs, and Bilsom Viking muffs; and one ANR muff, the Peltor 7004. Within each ear condition, measurements were made in quiet of hearing thresholds for frequencies between 0.25 kHz and 8 kHz, duration and frequency difference limens, and word recognition. Hearing thresholds and word recognition were also measured in a background of impulsive cable swager noise. The E-A-R foam plug provided the highest and the E-A-R HI-FI plug, the lowest attenuation. The Bilsom Viking and Peltor muffs were virtually identical and midway between. An additional 10 dB of sound reduction was realized at 0.25 kHz with ANR. The masking effect of the noise on hearing threshold decreased with an increase in attenuation. None of the devices compromised either duration or frequency discrimination. Word recognition in noise improved in normal listeners when protectors were worn. For the impaired subjects, word recognition with poor contextual cues decreased with an increase in sound attenuation, in both quiet and noise. Like older normal listeners, their scores were relatively higher with ANR.
在两组听力正常的受试者（年龄分别在40岁以下和40岁以上）以及一组双侧高音听力损失的受试者中，对主动降噪（ANR）听力保护器的益处进行了评估。受试者在耳朵未堵塞的情况下进行测试，并佩戴传统的隔音E-A-R泡沫耳塞、E-A-R HI-FI耳塞和Bilsom Viking耳罩；以及一种ANR耳罩，即Peltor 7004。在每种耳部条件下，测量了0.25 kHz至8 kHz频率范围内的安静环境下的听力阈值、时长和频率差异阈限以及单词识别能力。还在脉冲电缆压接机噪声背景下测量了听力阈值和单词识别能力。E-A-R泡沫耳塞提供了最高的衰减，而E-A-R HI-FI耳塞提供了最低的衰减。Bilsom Viking耳罩和Peltor耳罩几乎相同，处于两者之间。使用ANR在0.25 kHz时可额外实现10 dB的降噪。噪声对听力阈值的掩蔽效应随着衰减的增加而降低。没有一种设备会损害时长或频率辨别能力。佩戴保护器时，正常听力者在噪声中的单词识别能力有所提高。对于听力受损的受试者，在安静和噪声环境中，上下文线索较差时的单词识别能力会随着声音衰减的增加而下降。与年长的正常听力者一样，他们使用ANR时的分数相对较高。
