In this work we have studied the effects on a four-wave mixing (FWM) signal of different apertures of two crossed harmonic curves in an intramolecular coupling model. These apertures are measured using the quotient between the resonant frequencies of two curves, Δ = ω̃ 0/ω0. We observed changes in intensity and position of the peaks present in the FWM signal spectra due to the variations in Δ. These changes are directly related to the behaviour of the resonant frequency and the dipole moments of the coupled states with the parameter Δ.