Centre for Hearing and Balance Studies, Bristol University, 5th Floor, 8 Woodland Road, Bristol BS8 1TN, England.
J Acoust Soc Am. 2012 Jun;131(6):4526-34. doi: 10.1121/1.4707457.
Three pairs of headphones [standard iPod ear buds and two noise-canceling headphones (NCHs)] were chosen to investigate frequency characteristics of noise reduction, together with their attenuation effects on preferred listening levels (PLLs) in the presence of various types of background noise. Twenty-six subjects with normal hearing chose their PLLs in quiet, street noise, and subway noise using the three headphones and with the noise-canceling system on/off. Both sets of NCHs reduced noise levels at mid- and high-frequencies. Further noise reductions occurred in low frequencies with the noise canceling system switched on. In street noise, both NCHs had similar noise reduction effects. In subway noise, better noise reduction effects were found in the expensive NCH and with noise-canceling on. A two way repeated measures analysis of variance showed that both listening conditions and headphone styles were significant influencing factors on the PLLs. Subjects tended to increase their PLLs as the background noise level increased. Compared with ear buds, PLLs obtained from NCHs-on in the presence of background noise were reduced up to 4 dB. Therefore, proper selection and use of NCHs appears beneficial in reducing the risk of hearing damage caused by high music listening levels in the presence of background noise.
选取了三副耳机（标准 iPod 耳塞和两副降噪耳机）来研究降噪的频率特性，以及在各种类型的背景噪声存在的情况下，它们对首选聆听水平（PLL）的衰减效果。26 名听力正常的受试者使用这三种耳机和降噪系统开/关，在安静、街道噪声和地铁噪声环境中选择自己的 PLL。两套 NCH 耳机都降低了中高频的噪声水平。当降噪系统打开时，低频的噪声进一步降低。在街道噪声中，两种 NCH 耳机的降噪效果相似。在地铁噪声中，昂贵的 NCH 和降噪系统开启时，降噪效果更好。双因素重复测量方差分析显示，听力条件和耳机样式都是影响 PLL 的重要因素。随着背景噪声水平的增加，受试者倾向于提高他们的 PLL。与耳塞相比，在背景噪声存在的情况下使用 NCH 时，PLL 降低了高达 4 分贝。因此，在背景噪声存在的情况下，选择和使用合适的 NCH 似乎有助于降低因高音乐聆听水平而导致听力损伤的风险。
