Master told me how much decibel is the noise of 800KVA transformer? Urgent! thank you

The noise of transformer must be controlled within 70 decibels.

Transformer is a device for converting AC voltage, current and impedance. When alternating current passes through the primary coil, alternating magnetic flux is generated in the iron core (or magnetic core), and voltage (or current) is induced in the secondary coil. A transformer consists of an iron core (or magnetic core) and a coil. The coil has two or more windings, of which the winding connected to the power supply is called the primary coil and the rest is called the secondary coil. In the generator, whether the coil moves through a magnetic field or a fixed coil, an electric potential can be induced in the coil. In both cases, the value of magnetic flux remains the same, but the amount of magnetic flux in the chain intersecting with the coil changes, which is the principle of mutual inductance.