The Effects of Noise from the Subway Cars on the Preferred Listening Volumes and Noise Exposure Using Earphones / 听力学及言语疾病杂志

ABSTRACT

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.