McBride D I, Williams S
Institute of Occupational Health, University of Birmingham, UK.
Occup Environ Med. 2001 Jan;58(1):46-51. doi: 10.1136/oem.58.1.46.
To investigate the relation between different types of exposure to noise and a classic sign of noise induced hearing loss (NIHL), the audiometric notch.
The study sample had exposure to both continuous and impulse noise and was drawn from a population of electrical transmission workers. Audiograms, taken as part of a hearing conservation programme, were read by three clinicians experienced in the assessment of NIHL. Working independently and using their clinical judgment, they were asked to identify localised increases in the threshold of hearing (audiometric notches) which they would attribute to noise, had a suitable history of exposure been elicited. Prevalent cases of NIHL were identified by the presence of a notch in either ear. Risk factors for NIHL were assessed by a questionnaire which sought information about exposure to air blast circuit breaker noise; firearms; explosions, and continuous noise. The odds of exposure to these factors in those with and without hearing loss were calculated, and odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression.
Of the 648 questionnaires sent out 357 were returned, a response rate of 55%. Of these, at least two out of the three assessors identified 175 (49%) people with a notch at any audiometric frequency. There was no association between these cases and the NIHL risk factors identified by the questionnaire, but a further frequency specific analysis showed a small proportion of people (15 (4%)) with notches at 4 kHz who had the expected associations with exposure to noise and a significant OR for firearms of 4.25 (95% CI 1.28 to 14.1). The much larger proportion of people with 6 kHz notches (110 (31%)) did not show these associations.
To diagnose NIHL it is important to elicit a detailed and accurate history of exposure to noise: although the notch at 4 kHz is a well established clinical sign and may be valuable in confirming the diagnosis, the 6 kHz notch is variable and of limited importance.
研究不同类型的噪声暴露与噪声性听力损失（NIHL）的一个典型体征即听力图切迹之间的关系。
研究样本来自输电工人群体，他们同时暴露于连续噪声和脉冲噪声。作为听力保护计划的一部分所进行的听力图检查，由三位在NIHL评估方面经验丰富的临床医生进行解读。他们独立工作并运用临床判断，被要求识别听力阈值的局部升高（听力图切迹），如果能引出合适的暴露史，他们会将其归因于噪声。通过双耳中任一耳存在切迹来确定NIHL的现患病例。通过一份问卷评估NIHL的危险因素，该问卷旨在获取有关暴露于空气断路器噪声、火器、爆炸及连续噪声的信息。计算有听力损失者和无听力损失者暴露于这些因素的比值，并通过逻辑回归估计比值比（OR）和95%置信区间（95%CI）。
发出648份问卷，回收357份，回复率为55%。其中，三位评估者中至少有两位识别出175名（49%）在任何听力频率处有切迹的人。这些病例与问卷所确定的NIHL危险因素之间无关联，但进一步的频率特异性分析显示，一小部分（15名（4%））在4kHz处有切迹的人与噪声暴露有预期关联，火器暴露的显著OR为4.25（95%CI 1.28至14.1）。在6kHz处有切迹的人比例要大得多（110名（31%）），并未显示出这些关联。
要诊断NIHL，获取详细准确的噪声暴露史很重要：尽管4kHz处的切迹是一个公认的临床体征，可能对确诊有价值，但6kHz处的切迹变化不定且重要性有限。
