Output levels of commercially available portable compact disc players and the potential risk to hearing
Output levels of commercially available portable compact disc players and the potential risk to hearing
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DOI：
10.1097/00003446-200412000-00001
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发表时间：
2004-12-01
期刊：
影响因子：
3.7
通讯作者：
Cox, LC
中科院分区：
文献类型：
--
作者：
Fligor, BJ;Cox, LC
目的：测量市售便携式光盘播放器的耳机产生的声级，并为听力保健提供者提供基于理论噪声剂量模型的安全指南。设计：使用用于声学研究的楼氏电子人体模型和个人计算机，从标准信号（白噪声）驱动的耳机记录音量控制设置的输出电平，并与八种不同流派的音乐样本的输出电平进行比较。我们对来自不同制造商的许多市售型号进行了调查。使用几种不同样式的耳机（插入式、贴耳式、立式和包耳式）来确定耳机样式是否影响输出电平。结果：在最大音量控制设置下测得的自由场等效声压级范围为 91 dBA 至 121 dBA。输出电平因耳机制造商和款式的不同而不同，但通常耳机越小，给定音量控制设置的声级就越高。具体而言，在一家制造商中，相对于购买 CD 播放器时附带的库存耳机的输出，插入式耳机的输出电平提高了 7-9 dB。在一些耳机-CD 播放器组合中，峰值声压级超过 130 dB SPL。结论：根据测量的系统声压级以及美国国家职业安全与健康研究所推荐的用于保护职业工人的噪声剂量模型，使用贴耳式耳机将音量控制设置为最大增益的 70% 时，通常会在收听后 1 小时内达到最大允许噪声剂量。使用可提高输出电平的耳机（例如本研究中使用的插入式耳机）将显着降低最大安全音量控制设置；这种影响从一个制造商到另一个制造商都是不可预测的。为了提供保护大多数消费者听力的直接建议，合理的指南将包括建议：如果在增益控制设置为最大增益 60% 的情况下使用贴耳式耳机，则建议将每天使用耳机的时间限制在 1 小时或更少。
Objective: To measure the sound levels generated by the headphones of commercially available portable compact disc players and provide hearing healthcare providers with safety guidelines based on a theoretical noise dose model.Design: Using a Knowles Electronics Manikin for Acoustical Research and a personal computer, output levels across volume control settings were recorded from headphones driven by a standard signal (white noise) and compared with output levels from music samples of eight different genres. Many commercially available models from different manufacturers were investigated. Several different styles of headphones (insert, supra-aural, vertical, and circumaural) were used to determine if style of headphone influenced output level.Results: Free-field equivalent sound pressure levels measured at maximum volume control setting ranged from 91 dBA to 121 dBA. Output levels varied across manufacturers and style of headphone, although generally the smaller the headphone, the higher the sound level for a given volume control setting. Specifically, in one manufacturer, insert earphones increased output level 7-9 dB, relative to the output from stock headphones included in the purchase of the CD player. In a few headphone-CD player combinations, peak sound pressure levels exceeded 130 dB SPL.Conclusions: Based on measured sound pressure levels across systems and the noise dose model recommended by National Institute for Occupational Safety and Health for protecting the occupational worker, a maximum permissible noise dose would typically be reached within 1 hr of listening with the volume control set to 70% of maximum gain using supra-aural headphones. Using headphones that resulted in boosting the output level (e.g., insert earphones used in this study) would significantly decrease the maximum safe volume control setting; this effect was unpredictable from one manufacturer to another. In the interest of providing a straightforward recommendation that should protect the hearing of the majority of consumers, reasonable guidelines would include a recommendation to limit headphone use to 1 hr or less per day if using supra-aural style headphones at a gain control setting of 60% of maximum.