To determine the sound radiation power of devices in power stations and the contribution to enterprises noises

we measured the sound radiation power of several 1 000 kV Ultra High Voltage（UHV） transformers by a sound pressure and sound intensity methods. Results show that the sound power measured by the sound intensity method is 3～5 dB lower than that by the sound pressure method. Therefore

we propose a new combined method

which is based on the on-site vibration and sound pressure measurement

to determine the UHV transformer noise levels. It is found that the sound power measured by this method is closer to that by the sound pressure method

with only 0.75 dB averaged deviation

and has an error of 4.5 dB compared with that by the sound intensity method. Meanwhile

the measurement results show that this method possesses a good performance of anti-interference and is suitable for onsite measurement of the noise level for the UHV transformers. The method can effectively distinguish the noise resources of UHV transformers

and thus provide the technological support for treatment of noises from UHV transformers.