The noise of electrical machines such as electric motors, power transformers and electrical inductors increasingly interested designers and manufacturers of several industries (automotive, rail, etc.). This interest concerns the reduction of noise caused by these machines in transportation vehicles for example, to provide better comfort to users. In this paper, the noise radiated by an electrical power transformer is predicted using an end-to-end multiphysics modelling solution. The modelling procedure is based on the chaining of three analysis methods. The first one simulates the electromagnetic problem which generates Maxwell forces on the magnetic core of the transformer from electrical excitation. These forces are considered as an input for the mechanical problem solved by the finite element method (FEM) to calculate the acceleration field on the structure. Finally, these accelerations are considered as in input for the acoustic model to compute the noise radiation using the Boundary Element Method (BEM). Two models of the ferromagnetic core are considered. The first is a bloc model where the different laminates are stuck and the second is a laminated model where a small sliding condition is introduced at interfaces between sheets of metal. Numerical results of the mechanical and acoustic models using a laminated core are compared with experimental data and show good agreements with measurements.