AR model orders of lung sounds

Earlier studies of our group have demonstrated that autoregressive (AR) models clearly depend on flow and volume. In those studies the AR model order was fixed at 6. An evaluation has been made of the applicability of seven order selection criteria. The Finite sample Information Criterion (FIC) appears to be the best choice. The results also indicate that the true model order lies between 2 and 6. However, in general there are no major decreases in criterion values above order 3. This implies that it is justified to take a fixed order of 3 or 4.