聽力保護裝置之主客觀效益評估

聽力保護裝置所標示的噪音衰減率，係透過重複量測該裝置對各頻率噪音衰減量，並透過統計和修正運算所得到的結果，此結果往往和實際佩戴時所能產生之效益不盡相同。此外，若需要評估保護裝置對不同頻率噪音的防護表現，單一的噪音衰減率數值並無法提供相關資訊。本研究之目的是藉由無學習佩戴聽力保護裝置經驗的受測者，執行以聲學人偶（KEMAR）量測出客觀性噪音衰減率，並在實際佩戴保護裝置下，測量主觀性真耳聽閾減幅值，以檢視不同量測方式的差異。實驗結果顯示，被動耳罩式和被動入耳式保護裝置的噪音衰減率，較原廠實驗者所測得之數值約低10 dB；而重複量測各款裝置之噪音衰減率並計算其標準差，約在3.3 dB至 23.1 dB，顯示部分裝置重複佩戴時所能提供的噪音衰減效果一致性偏低。而從主觀性真耳聽閾減幅值的結果可知，不同裝置對各頻率的噪音有不同的衰減效果。結論：本研究建議提供聽力保護相關專業服務人員，於選擇適合的聽力保護裝置時，除參考包裝上所標示之噪音衰減率之外，應給予佩戴者正確使用聽力保護裝置的教育訓練，並教導自我評估是否已正確佩戴之測試方法，且實際量測佩戴後之真耳聽閾減幅值，以確保該聽力保護裝置對佩戴者提供足夠之保護效益。

關鍵字

真耳聽閾減幅值；噪音型聽力損失；噪音衰減率；聽力保護裝置

並列摘要

This research firstly aimed to examine potential discrepancies between the noise reduction rating (NRR) provided by the manufacturers of hearing protection devices (HPDs) and that measured by inexperienced users, and then we had these subjects fit the HPDs on themselves, and measured the real-ear attenuation at thresholds (REAT) from 125 to 8,000 Hz. The NRR listed on the package of a HPD is generally measured by experienced experimenter (experiment-fit, EF) and represents the level of noise reduction achieved by the HPD in laboratory tests. In this study, we had inexperienced subjects fit (ISF) HPDs on Knowles Electronics Manikin for Acoustic Research (KEMAR), and then repeatedly measured the noise reduction levels to derive the NRR (ISF) for each HPD. The results showed that the mean NRR (ISF) of the supra-aural and insert-ear HPDs with passive noise reduction evaluated in this study was 10 dB less than the NRR (EF) given by the manufacturer. Additionally, the foam earplug had the highest standard deviation of NRR (ISF) at 23 dB, which indicated that the earplug had low NRR (ISF) consistency. Afterwards, we had these subjects fit the HPDs on themselves, and measured the real-ear attenuation at thresholds (REAT) from 125 to 8,000 Hz, with and without the HPDs. The REAT of each HPD revealed that the attenuation of HPDs varied with the frequency. In contrast to the REAT, The NRR is a single value that summarizes the level of noise reduction at measured frequencies and thus does not reveal noise attenuation information at specific frequency channels when evaluating the efficacy of HPDs. In conclusion, this study suggests that hearing conservation supervisors should not only take the listed NRR (EF) into consideration but also provide HPD users with training on correct use of HPDs and REAT measurements to ensure the efficacy of HPDs on users.