Chao, Effect of Low Frequency Noise on the Echocardiographic Parameter

Chao, Pao-Chiang; Yeh, Ching-Ying; Juang, Yow-Jer; Hu, Ching-Yao; and Chen, Chiou-Jong, Taiwan 2012

The hearing condition of the Taiwanese aerospace maintenance workers affected by the low frequency noise had not been reported. The purpose of this research is to clarify the maintenance workers’ health effect when exposed to low frequency and/or general noises and to understand the relationship between the variations of the worker’s echocardiographic E/A ratio and the low frequency noise.

The low frequency noise monitoring and echocardiographic E/A ratio results obtained for 213 aerospace maintenance workers indicated that the workers’ hearing loss was more serious at high frequency 4k and 6k when exposed to the low frequency noise and could be more than 40 dB. The abnormality of echocardiographic E/A ratio was also higher than that of control group.

Industrial noise has various effects on human psychological as well as physical health, and the frequency of the noise plays a vital role. Taiwan’s Environmental Protection Agency defines low frequency noise in the range from 20 Hz to 200 Hz. In general, a noise with the frequency less than 20 Hz is called infrasound. It may not be easy to detect, but it does exist in our living environment and may impose adverse effects on our health. Low frequency noise is not as “allergic” to human ears as high frequency noise.

In Taiwan, the effect of noise on the human hearing condition (such as hearing loss) has been investigated extensively. However, the studies on the effect of low frequency noise on human non-hearing conditions such as cardiac status were not found. Echocardiography has been used in clinical medicines since 1960. Castelo Branco applied echocardiography to access vibroacoustic disease (VAD). Currently, echocardiography is the best choice to access the diastolic function of the left ventricle (LV), and many parameters of this method have been developed to access the LV function. One of the parameters is the transmitral flow velocity, which is fairly easy to obtain and can detect the thicken conditions of LV and pericardium. Echocardiography is a cardiac non-invasive inspection method.

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