地铁车厢内噪声对不同类型耳机佩带舒适音量的影响

摘要

Objective To investigate the effects of noise from the subway cars on the preferred listening volumes using different kinds of earphones.Methods A total of 75 subjects with normal hearing were investigated to listen the same song wearing 4 kinds of earphones: insert earphones, intra-concha earphones, supra-concha earphones, and circumaural earphones, in the semi-anechoic background and inside the Line 7 subway-cars of the Beijing subway (the mean of LAeq,1s is 80.3 dB A and then selected personally preferred listening volumes.The effects of noise in the subway cars and earphone types on the preferred listening volumes were then analyzed.Results Inside subway-cars, the preferred listening levels using insert earphones, intra-concha earphones, supra-concha earphones, circumaural earphones were 76.6±4.7, 84.3±5.0, 82.3±4.2, and 80.8±4.2 dB A, respectively.The levels were respectively 65.5±6.8, 71.9±7.1, 69.5±7.5, 67.9±7.3 dB A for those in the semi-anechoic background.The preferred listening levels increase more than 10 dB averagely when stepped into noisy subway-cars background from silent background.According to the threshold levels stipulated in the WHO, to avoid hearing impairment, the daily noise exposure duration should not exceed 134 mins when exposed to subway-cars noise and the duration should not exceed 315, 54, 85, and 120 mins respectively when wearing those 4 kinds of earphones in subway-cars.Conclusion The noise and earphones types have great effects on the preferred listening volumes.The noise exposure levels in the ear canal wearing earphones with good sound insulation and listening at highly increased volume may be lower than that without earphones.%目的 探讨地铁车厢内噪声对不同类型耳机佩戴者使用音量的影响.方法 以75例听力正常受试者为研究对象,每例对象分别佩戴入耳式、耳塞式、贴耳式和耳罩式耳机,在安静环境和北京地铁7号线车厢背景噪声(LAeq,1s均值为80.3 dB A)下听同一首音乐,选择舒适的音量档位,分析背景噪声、耳机类型对受试者耳机使用音量的影响.结果 在地铁车厢噪声环境下,受试者使用入耳式、耳塞式、贴耳式和耳罩式耳机选择舒适音量时人耳处噪声值分别为76.6±4.7、84.3±5.0、82.3±4.2、80.8±4.2 dB A,安静环境下分别为65.5±6.8、71.9±7.1、69.5±7.5、67.9±7.3 dB A;从安静环境到地铁车厢噪声环境,受试者的舒适音量平均提高了10 dB A以上.根据WHO噪声性聋的限值计算得到,不佩戴耳机每天暴露在上述地铁车厢背景噪声下不超过134 mins,使用上述耳机时时长分别不超过315、54、85、120 mins,可以避免噪声性听力损伤的发生.结论 地铁车厢噪声和耳机类型对耳机使用者舒适音量的影响较大;在地铁车厢嘈杂环境中,使用隔声性能较好的入耳式耳机,尽管调高了耳机舒适音量,人耳处实际噪声暴露水平仍可能低于不使用耳机时车厢噪声水平.