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声刺激引起中耳肌肉收缩所造成的声阻抗变化可以自鼓膜外面测出。文献资料表明中耳肌肉收缩对听阈的影响范围变动于30～35dB到低于5dB之间,本文的目的就是研究中耳肌肉收缩对纯音敏感度的影响。作者们对12名年龄在20～60岁之间的感觉神经性聋(8例双耳,4例单耳)患者用MadsenZ070电桥作阻抗测定,用Békésy听力计作各种不同实验条件下的纯音阈值测定,并应用适合所有阈值测定条件及听反射测定的白噪声。用Bel-tone CR 5000听力计作常规的纯音和语言测听。所有仪器均经定时校准。为确定听反射对纯音阈值的影响,受试者均需在以下三个条件下使用Békésy听力计测定纯音阈值。(1)不用掩蔽时测纯音阈值。(2)对侧耳用低于噪声反射阈值20dB的白噪声时测阈值,以显出中枢掩蔽的作用。这样,在上述两种条件下所测得的阈值差就提示为中枢掩蔽作用。(3)对侧耳用高于噪声反射阈值
Acoustic stimulation caused by contraction of the middle ear caused by acoustic impedance changes can be measured from the outer tympanic membrane. The literature shows that the effect of middle ear muscle contraction on the hearing threshold varies between 30-35 dB and below 5 dB. The purpose of this paper is to study the effect of middle-ear muscle contraction on pure tone sensitivity. The authors measured the impedance of 12 Madsen Z070 bridges in 12 patients with sensory deafness (8 ears, 4 ears) aged 20-60 years using the Békésy audiometer for various experimental conditions Pure tone threshold determination and application of white noise suitable for all threshold determination conditions and audiometry. The Bel-tone CR 5000 audiometer is used for regular pure tone and language audiometry. All instruments are regularly calibrated. To determine the effect of audible reflections on pure tone thresholds, participants were required to measure pure tone thresholds using a Békésy audiometer under the following three conditions. (1) pure tone threshold without masking. (2) Contralateral ear with white noise below the noise reflection threshold of 20dB when measured threshold to show the role of the central masking. Thus, the threshold difference measured under these two conditions suggests a central masking effect. (3) Contralateral ear higher than the noise reflection threshold