We propose a new empirical method of band shape calculations which takes into account line mixing effects. The proposed shape is based on the strong collision model with attenuated interbranch coupling. Apart from the conventional set of spectral line parameters one needs only one additional parameter to account for line mixing effects in band profile calculations. This parameter depends on the perturbing gas type. It is the same for all molecular infrared absorption bands. The new shapes are shown to be successful in representing the measured absorption bands of CO₂ in nitrogen (v₂, v₃, v₂ + 2v₃, 2v₂ - v₂, and 2v₁ - v₂) and the 3.6 μm band of O₃ in nitrogen.