Baes Travis, Ludwigsen Daniel, Sardelli Matthew, Atkinson Patrick, Atkinson Theresa Staton
Travis Baes, MD, Department of Orthopaedic Surgery, McLaren-Flint, Flint, MI.
Daniel Ludwigsen, PhD, Department of Physics, Kettering University, Flint, MI.
Orthop Nurs. 2021;40(4):240-245. doi: 10.1097/NOR.0000000000000774.
Hearing protection devices reduce cast-saw noise. It would be helpful to identify the devices that are both effective and economical. Prior studies have shown that expensive noise-reduction headphones significantly reduced the anxiety associated with cast removal with a powered oscillating saw. The cost of such headphones, however, is a drawback for some practices and hospitals. It would be helpful to determine whether lower cost ear protection can provide effective cast-saw noise reduction. In addition, it is unclear whether the noise reduction ratings (NRRs), the average sound-level reduction provided by a hearing protection device in a laboratory test, provided by manufacturers accurately characterize the effectiveness for reducing cast-saw noise. Note that noise-cancelling devices do not carry an NRR because they are not designed as hearing protectors. Five ear protection devices with different NNRs were tested. The devices varied greatly in cost and included earplugs, low-cost earmuffs, and noise-cancelling headphones. To standardize the evaluation, each device was fitted to an acoustic mannequin with high-fidelity ear microphones while a fiberglass spica cast was cut. An additional test was run without hearing protection as a control. The low-cost devices significantly reduced the saw noise, with the exception of earplugs, which had highly variable performance. The noise reduction was similar between low-cost earmuffs and the high-cost earphones when the noise-cancelling feature was not active. Active noise cancelling provided further reductions in the noise level. Patients can experience high anxiety during cast removal. The current study shows that low-cost earmuffs significantly reduce cast-saw noise. Patient care settings may be more likely to offer hearing protection that is one twenty-fifth the cost of noise-cancelling headphones. An NRR appears to be a reliable guide for selecting hearing protection that reduces cast-saw noise.
听力保护装置可降低石膏锯的噪音。识别出既有效又经济的装置会很有帮助。先前的研究表明，昂贵的降噪耳机能显著降低使用电动摆动锯拆除石膏时的焦虑感。然而，这类耳机的成本对一些诊所和医院来说是个缺点。确定低成本的耳部保护装置能否有效降低石膏锯的噪音会很有帮助。此外，尚不清楚制造商提供的降噪评级（NRR），即在实验室测试中听力保护装置提供的平均声级降低量，能否准确表征降低石膏锯噪音的效果。请注意，降噪装置没有NRR，因为它们并非设计为听力保护器。对五种具有不同NRR的耳部保护装置进行了测试。这些装置在成本上差异很大，包括耳塞、低成本耳罩和降噪耳机。为了使评估标准化，在切割玻璃纤维管型石膏时，将每个装置安装到带有高保真耳部麦克风的声学人体模型上。另外进行了一次不使用听力保护装置的测试作为对照。除了性能高度可变的耳塞外，低成本装置显著降低了锯的噪音。当降噪功能未开启时，低成本耳罩和高成本耳机的降噪效果相似。主动降噪进一步降低了噪音水平。患者在拆除石膏时可能会经历高度焦虑。当前的研究表明，低成本耳罩能显著降低石膏锯的噪音。患者护理场所可能更倾向于提供成本仅为降噪耳机二十五分之一的听力保护装置。NRR似乎是选择能降低石膏锯噪音的听力保护装置的可靠指南。
