Abstarct: Acoustic noise is the effect of a vibrating surface, so acoustic noise and vibration are two interconnected phenomena in electric machines and the sources of both are the same.The source of noise in electric machines can be divided into three categories: aerodynamic, mechanical and electromagnetic. With a very careful study, it can be boldly said that the source of vibration and sound noise in small to medium electric machines is the electromagnetic source and in large machines is the mechanical sources . Coging torque, torque ripple, and magnetic radial forces are the main sources of electromagnetic noise.It is very important to know at what frequencies the various components of radial forces are produced, if one of these frequencies is equal to or close to the normal frequency of the machine, intensification occurs and vibration and noise increase.Research has shown that changing the structure of the winding can change the radial and tangential forces on the surface of the stator teeth, so that an optimal amount of motor noise can be achieved and up to Decreased the desired amount.The main problem with permanent magnet machines is that the permanent magnets on the rotor are not formable, so they are not suitable for high speeds, so these types of machines are more useful at low speeds.In designing the machine to reduce its speed, two general solutions can be done: 1- Reducing the frequency: which leads to increasing losses and volume of the machine. 2- Increasing the number of poles: which also increases with the problem of arranging permanent magnets. The number of rotor poles, the number of slots increases and the stator strength decreases. To solve the above problems, we use a modular structure, in which in this structure a special harmonic is amplified instead of the main harmonic, and therefore the number of pairs of rotor poles is equal to the amplified harmonic. Therefore, without increasing the number of stator slots, the number of poles can be increased and the mentioned problems can be solved.