The influence of low-frequency noise on health of the residents along UHV AC transmission line corridor cannot be ignored. Especially

the influence of AC pure sound is worse due to its longer propagation distance and slower attenuation.In order to understand the distribution law and influence of AC pure sound

this study measured three kinds of pure acoustic frequency noise of respective 50

100

and 200 Hz under the straight-line tower and strain tower of UHV AC double-circuit transmission line on the same tower

and obtained the corresponding spectrum histogram

waterfall chart

and electromagnetic field versus distance curve.The change law of different frequency noise with the distance was analyzed.The results showed that the noise with different low frequency exhibited discrepant attenuation according to the distance from the line center

and the maximum 50 Hz noises were 42.4 d B and 49.3 d B at line center and the position 20 meters away from the side-phase conductor

respectively

which were both within the limit of noise emission standard in the daytime for industrial enterprises.Analysis on DTH sound and measurement of electric field at certain height of umbrella surface prove that the electric field is susceptible to distortion to produce audible noise

and the 4 kV/m is the very electric field intensity starting to produce noise when human or other objects move under the transmission line.