Stokes J P, Royster L H, Pearson R G, Royster J D
International Business Machines Corporation Inc., Palo Alto, CA 94304.
Am Ind Hyg Assoc J. 1991 Feb;52(2):52-60. doi: 10.1080/15298669191364325.
Subjective user responses were obtained for a test earmuff exhibiting approximately flat (uniform) attenuation of about 25 dB from 500 to 8000 Hz for sound pressure levels (SPLs) less than 120 dB. At SPLs above 120 dB, the test earmuff exhibited nonlinear (level-dependent) attenuation characteristics such that noise reduction increased with increasing sound level. The study population consisted of police officers from the Raleigh, North Carolina, Police Department as they were performing arms requalification by executing a series of firing programs during two sequential and identical relays. The study subjects wore either the test earmuff or a comparable conventional earmuff during the first relay, then the alternate protector for the second relay with the order counterbalanced. Results indicated a significant preference for the test earmuff in three comparison areas: comfort, perceived hearing protection, and speech understanding. The study demonstrates that ammunition type and level of noise exposure contributed significantly to a preference in favor of the test earmuff. The subjects who used the quietest of the ammunition types rated the test earmuff significantly better than the remaining subjects with respect to speech understanding.
针对一款测试用耳罩收集了主观用户反馈。该耳罩在声压级（SPL）低于120 dB时，从500至8000 Hz呈现出约25 dB的近似平坦（均匀）衰减。在声压级高于120 dB时，测试用耳罩呈现出非线性（与声级相关）衰减特性，即降噪效果随声级增加而增强。研究对象包括北卡罗来纳州罗利市警察局的警察，他们在连续两轮相同的射击训练中执行一系列射击项目以进行武器资格重新认定。在第一轮训练中，研究对象佩戴测试用耳罩或类似的传统耳罩，然后在第二轮训练中佩戴另一种防护装备，佩戴顺序相互平衡。结果表明，在舒适度、感知听力保护和言语理解这三个比较方面，测试用耳罩具有显著优势。该研究表明，弹药类型和噪声暴露水平对测试用耳罩的偏好有显著影响。就言语理解而言，使用最安静弹药类型的受试者对测试用耳罩的评价明显高于其他受试者。
