Shotland L I
National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Acoust Soc Am. 1996 Feb;99(2):979-84. doi: 10.1121/1.414626.
Federal and international standards recommended use of microphone placement either on or in the vicinity of the shoulder for dosimetry to minimize deviations from the undisturbed sound field. Probe microphone measurements from the ear canal were compared to shoulder and chest measures in order to investigate the validity of current dosimetry methodologies. Six subjects were monitored in an industrial setting. As expected, ear-canal levels exceeded other measures for all subjects. Shoulder and chest measures showed very low intersubject variability whereas ear-canal measures resulted in large intersubject variability. The ear-canal methodology has the potential to identify individuals whose external ear gain exceed the mean, putting them at increased risk of noise-induced permanent threshold shift (NIPTS). It is proposed that overall external ear pressure gain be used as an index to adjust exposure levels when predicting NIPTS using ISO 1999. A normative database of external ear pressure gain was constructed from 30 ears for this purpose.
联邦和国际标准建议在剂量测定时，将麦克风放置在肩部或其附近，以尽量减少与未受干扰声场的偏差。将来自耳道的探头麦克风测量结果与肩部和胸部的测量结果进行比较，以研究当前剂量测定方法的有效性。在工业环境中对6名受试者进行了监测。正如预期的那样，所有受试者的耳道水平均超过其他测量值。肩部和胸部测量显示受试者间变异性非常低，而耳道测量导致受试者间变异性很大。耳道测量方法有可能识别出外耳道增益超过平均值的个体，使他们面临噪声性永久性阈移（NIPTS）风险增加。建议在使用ISO 1999预测NIPTS时，将外耳道总压力增益用作调整暴露水平的指标。为此，从30只耳朵构建了外耳道压力增益的标准数据库。
