The Maxwell pressure is the cause of stator deflection at the origin of acoustic noise radiated by stator. That is why precise determination of air-gap radial flux density B g is of prime importance. It could be obtained by finite element method, semi numerical or totally analytic method with computation of magneto motive force and permeance. Slot numbers, eccentricity and saturation affecting acoustic behavior can be included in permeance computation with analytic method.