当前FDA非处方助听器指南允许的极大验配范围和危险声级以及考虑RECD的必要性

文献信息

中文摘要

背景/目的： 美国FDA的使命之一是“通过确保人用和兽用药物、生物制品的安全性、有效性和保障性来保护公众健康”。当前的非处方助听器指南规定，在使用2 cc耦合腔、以90 dB SPL纯音测量时，线性助听器的输出限值为111 dB SPL，压缩助听器为117 dB SPL。这意味着某一频率下鼓膜处的声压级将为111或117 dB SPL加上该频率下2 cc耦合腔的真耳-耦合腔差值（RECD）。方法：使用NAL-NL2和DSLv5验配方法，探讨了符合当前FDA指南的假设性非处方压缩助听器可助听的最大听力阈值。还计算了耳道内理论最大允许总输出声级。此外，探讨了鼓膜处最大输出声级为117 dB SPL的非处方压缩助听器的验配范围。结果：当前FDA指南允许非处方压缩助听器提供足够的增益和余量，以验配重度至极重度听力损失个体。在存在响亮宽带信号时，对于带宽为5657 Hz的非处方压缩助听器，耳道内最大总输出声级可达到164.5 dB SPL。然而，当最大输出声级定义在鼓膜处（即已考虑RECD）时，验配范围降至中度听力损失，最大总输出声级降低10 dB。结论：这些发现识别了当前FDA指南中潜在的监管漏洞，并建议在制定非处方助听器指南时考虑测量耦合腔及其相应的RECD。还讨论了防止指南潜在滥用的其他替代策略。

英文摘要

Background/Objective: One of the missions of the United States FDA is "protecting the public health by ensuring the safety, efficacy, and security of human and veterinary drugs, biological products." The current guidelines for OTC hearing aids impose an output limit of 111 dB SPL for linear hearing aids and 117 dB SPL for compression hearing aids when measured using 90 dB SPL pure tones in a 2 cc coupler. This means that the sound pressure level at the ear drum at a frequency would be 111 or 117 dB SPL plus the real-ear-to-coupler difference (RECD) of the 2 cc coupler at the frequency. Methods: The maximum aidable hearing thresholds by hypothetical OTC-compression hearing aids that are compliant with the current FDA guidelines were explored using NAL-NL2 and DSLv5 prescriptive methods. The theoretical maximum permissible overall output levels in the ear canal were also calculated. Additionally, the fitting range of OTC-compression hearing aids with a maximum of 117 dB SPL output level at the ear drum was explored. Results: The current FDA guidelines allow OTC-compression hearing aids to provide sufficient gain and headroom to fit individuals with severe to profound hearing loss. In the presence of a loud wideband signal, the maximum overall output level can reach 164.5 dB SPL in the ear canal for an OTC-compression hearing aid with a bandwidth of 5657 Hz. When the maximum output levels are defined at the ear drum (i.e., the RECD is already considered), however, the fitting range is lowered to moderate hearing loss and the maximum overall output level is lowered by 10 dB. Conclusions: These findings identified potential regulatory vulnerability in the current FDA guidelines and suggest the need to take the measurement coupler and its corresponding RECDs into account when setting the guidelines for OTC hearing aids. Other alternative strategies to prevent potential abuses of the guidelines are also discussed.