Wang L
Havy General Hospital, Beijing.
Zhonghua Er Bi Yan Hou Ke Za Zhi. 1990 Oct;25(5):277-80, 318.
So far there have been few studies on the effect of low frequency noise on auditory organs. Twenty-four Preyer's reflex normal guinea pigs were exposed to the octave bands of noise at 63 Hz and 4 kHz, 110 dB A (SPL). The durations of exposure were 4 and 8 hr. It was discovered that the permanent threshold shift for both frequencies was at 4-8 kHz. In guinea pigs exposed 4 hrs, the threshold shift for 63 Hz was smaller than that for 4 kHz, while the threshold shift for 63 Hz in guinea pigs exposed 8 hr was similar to that of 4 kHz. No change in inner ear morphology was observed in guinea pigs exposed 4 hrs to the octave band of noise at 63 Hz and 4 kHz, but ultrastructural abnormality was demonstrated. When the animal was exposed 8 hr, changes in inner ear morphology and ultrastructure were seen. The main pathological changes were at the second coil of the cochlea. The auditory changes suggest that an intensive low frequency noise may induce a high frequency hearing loss. The result also indicates that using A-weighted level to determine the damage risk criteria of noise is inappropriate.
到目前为止，关于低频噪声对听觉器官影响的研究很少。将24只普赖尔反射正常的豚鼠暴露于63赫兹和4千赫兹的倍频程噪声中，声压级为110分贝A（声压级）。暴露持续时间为4小时和8小时。发现两个频率的永久性阈移都出现在4 - 8千赫兹。在暴露4小时的豚鼠中，63赫兹的阈移小于4千赫兹的阈移，而暴露8小时的豚鼠中，63赫兹的阈移与4千赫兹的相似。在暴露于63赫兹和4千赫兹倍频程噪声4小时的豚鼠中，未观察到内耳形态变化，但显示有超微结构异常。当动物暴露8小时时，可见内耳形态和超微结构的变化。主要病理变化位于耳蜗的第二圈。听觉变化表明，强烈的低频噪声可能导致高频听力损失。结果还表明，使用A加权声级来确定噪声的损害风险标准是不合适的。
