Abstract: A hybrid computational aeroacoustics technique was performed to investigate the aerodynamic noise characteristics of a three-element airfoil. The aerodynamic source was simulated with an improved delayed detached eddy simulation (IDDES) method and the far-field aerodynamic noise was computed by Curle's equation. The noise generated by a low Mach number flow past the rod-airfoil configuration was evaluated by the numerical approach and compared with the experimental data. The comparison shows that IDDES method can accurately describe the flow characteristics including the vortex shedding, detachment and reattachment, and provide detailed sources for the prediction of the acoustic far-field. The Curle's equation can evaluate the far-field noise accurately and efficiently. The quadrupole source can be neglected for the acoustic far-field of a low Mach number flow. Therefore, the aeroacoustics and aerodynamics characteristics of the three-element airfoil at Reynolds number of 1.71×10⁶, Mach number 0.17 and angle of attack 7.5° were analyzed. The pressure fluctuation on the surface of the flap exerts largest influence on the acoustic far-field while the slat exerts minimum. The peak values of the noise near 1000 Hz are generated by the shear layer flow separation and the vortex shedding at the trailing edge of the flap. The vortex shedding, fusion and collision in the slat cove mainly induce noise below 500 Hz. The noises near 4500 Hz are resulted from the vortex shedding at the trailing edge of the flap and the flow separation at the trailing edge of the main wing suction surface.